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USEFUL INFOEMATION FOR ENGINEERS

SECOND SEBrES

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USEFUL

INFORMATION FOR ENGIN

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THB COLL1.PSB OB BOILBB VLVB8 AKS THB 8TBXV6TK OB

MATBBULLS, ASD LBCTUBBS OK POBirLi.B BSVCAXIOIT AKD TABIOUS BUBJBOn

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BUILDIira, THB 7B0PBBTIX8 OB 8TBA1C, XTO.

L BY

5ir WILLIAM^ PAIRBAIRN, LL.D. P.R.S.

Corresponding Member of the National Institute of France, Chevalier of the Legion of Honour,

Member of the Royal Academy of Turin, &c.

LONDON
LONGMAN, GREEN, LONGMA]^, AND ROBERTS

1860

(

MAJOR-GENERAL EDWARD SABINE

R.A<( D.O.L.i F.R.S.) F.L.8*

u HoF. Mbv. Cam. Phil. Soo., Obs. Bobttsb. * Pour It M4HU' Eq. it ACUD. RlO. BlBOK.*

^ ACADS. IKP. So. PSTBOPm BBITZ.. NOBT.. BTO.

BY THE ATJTHOB

AS A MARK OF PBRSONAL B8TBBM
AND AS A TESTIMONY TO HIS BMINBNT SCIBNTIFIO ATTAINMBNTS AND

DISTINOUISHBD SBRVICBS IN THB
PROMOTION AND EXTENSION OF USEFUL KNOWLBDOB

PREFACE.

The great success which has attended the issue of the
first series of Lectures, under the title of Useful Infor-
mation for Engineers, has induced me to publish the pre-
sent volume, in which will be found various original
papers not before printed, or not easily accessible to or-
dinary readers.

In the discourse on the education of working men, I
have shown what a wide field is still open for talent com-
bined with industry and perseverance in the attainment of
distinction in science and art. I have not hesitated to en-
courage the young aspirant to prepare himself by mental
culture and vigorous exertion for the realisation of an
honourable name in the voyage of life. To awake an
honest ambition, and to render sensible latent talents, were
the objects of various addresses delivered from time to
time in various Institutes, and I flatter myself that the
reader will not blame me for seeking to give a wider cir-
culation and a more permanent value to such an attempt
than was possible in an oral lecture. I hope that in stim-
ulating working men to cultivate their powers to the
highest point of development, I have not ventured beyond
professional duty, and that the reader will sympathise with

Vlll PBEFAOB*

me in the wish to raise the working men of this kingdom
to a higher state of intellectual culture than they have
heretofore attained in their relations to society and the
domestic circles by which they are surrounded.

Leavings however^ the question of popular education to
abler hands^ I would now direct attention to the papers on
the Collapse of Tubes, in which will be found not only the
first investigation of the conditions of rupture in vessels
exposed to uniform external pressure, but also an entirely
new law of resistance, fully determined by direct experi-
ments. The results recorded in these papers bear directly
on the daily practice of the Engineer. The law that the
resistance is inversely as the length of the tube exposed to
pressure, is both of great importance and wide application ;
in a word, it should be kept in view in every construction
where tubes exposed to external pressure form the whole
or a part of the design.

In the paper on the Resistance of Glass Globes and
Cylinders to Collapse from External Pressure, and on the
Tensile and Compressive Strength of various kinds of
Glass, I have sought to confirm the previous experiments
on wrought iron tubes, by experiments on a perfectly
homogeneous material. At the same time, as the mechan-
ical properties of glass have been hitherto little known, the
paper has been rendered more complete by experiments
on the tensile and compressive strength, which I hope
may prove valuable to those who are engaged in scientific
investigations. We are still very deficient in our know-
ledge of the laws of contraction in bodies passing from the
fluid to the solid state, and the effect of internal strains
arising from unequal contraction on the cohesive strength

PBEFACE. IX

of the material. That such strains exist to an injurious
extent is often seen in cast iron^ and was found to exist to
a still greater extent in the experiments on glass. Let ut
hope that further researches may be made on this point,
and greater certainty secured in metallic constructions,
under the influence of temperatures producing in succession
the fluid, the semi-fluid, and the solid state.

On the influence of temperature on the cohesive strength
of wrought iron I made, some time ago, the experiments
recorded in the succeeding paper. These extend from
below zero to a dull red heat, and will, I trust, be found of
Talue in showing the conditions in which the material can
be trusted when exposed to increased or diminished tem-
peratures.

I have reprinted the paper on the Compressive Strength
of Brick and Stone for the guidance of the engineer and
architect, and they may safely be relied upon in calculating
the strength of piers, walls, and other structures where
these materials are employed.

The Lecture on the Machinery employed in Agriculture
was undertaken at the request of several distinguished
agriculturalists, and amongst them the Eight Honourable
the Speaker of the House of Commons. In this brief
treatise I have endeavoured to point out the defects of our
present improved and improving system, and to propose
remedies for them. I have especially urged upon the
farmer the value and necessity of machine culture, in order
to increase the productiveness of the soil, and to secure
the crops with greater certainty and despatch. I have
directed attention to the state of the land, and the im-
provements required before machine culture can be effi-

X PBEFACE.

ciently employed^ and I have concluded with the expression
of a belief that the English agriculturalist might be very
much benefited by availing himself of the appliances
which the present advanced state of mechanical science has
placed at his disposal.

The Lectures on the Eise and Progress of Civil and
Mechanical Engineering were intended for the information
and encouragement of the members of several combined
institutions at Derby ; they are historical and descriptive^
and having been personally concerned in the promotion of
some of the works described, I am perhaps better able to
supply the material and fill up the gap between the present
and that period which belongs to the past history of en-
gineering art.

The Lectures on Iron Shipbuilding are on a question of
such deep importance that I make no apology for their
introduction into this series. When it is known that the
most disastrous and fatal consequences have followed from
the construction of vessels on erroneous principles, and
that thousands of lives are at the mercy of our naval
engineers and architects, assuredly it is essential to the in-
terests of humanity that defects and errors of construction
should be pointed out and sounder principles applied. If
we examine closely into the state of iron shipbuilding, it
will be found that numbers of vessels are built and are now
afloat which are perfectly unseaworthy, that our knowledge
of first principles is far from perfect, and that a remedy
should be immediately applied to avert the calamitous and
fatal shipwrecks which so frequently fill the columns of the
public prints.

Impressed with the conviction that these lamentable

PREFACE. XI

catastrophes might be in some cases averted^ I was induced
to yenture on the inquiry, and finding that a want of
foresight in the builder, or a want of knowledge of the
conditions of rupture of iron vessels on the present prin-
ciple of construction appeared to exist, I lost no time in
applying the results of my own experiments on girders to
this case, and submitted my conclusions to the shipowners
of Liverpool and the members of the Polytechnic Institute
of that town. The same paper was subsequently read
before the Institute of Naval Architects in London, and
forms the fifth lecture of the present volume.

In the sixth lecture I have applied the same principles
to vessels of still larger size, where a modified form of
construction appeared necessary. I earnestly hope that
the views thus recorded may lead to further inqiury, and
subsequently to a class of experiments calculated to ensure
safety, and that with a more correct and judicious distri-
bution of the material and more exact principles of con-
struction*

It was originally my intention in the publication of this
series to have resumed an inquiry into the properties of
steam. This experimental investigation has occupied my
attention, along with that of my friend and colleague Mn
Thomas Tate, for the last three years, and although we
have arrived at important results in regard to density and
expansion, up to 60 lbs. pressure per square inch, we are
short of data for extending them to higher pressures and a
greater degree of superheating, and the experiments, al-
though in progress, are not yet in a condition suitable for
publication. A resume of the results already obtained
will, however, be found embodied in Lecture Vltl., ex-

Xll PREFACE.

tracted from our joint paper in course of publication by
the Boyal Society.

Amongst other constructions of a useful and practical
character^ I have introduced a description of the tubular
cranes^ so admirably adapted for lifting heavy goods> and
swinging them round over a circle of large radius.

In this statement it now only remains for me to express
my acknowledgments to the Councils of the Boyal
Society and the British Association for the Advancement
of Science, for the readiness with which they granted
permission to republish some of my papers in the present
volume. Also to my friend Mr. T. Tate, who is ever
willing to assist me with his superior mathematical attain-
ments. I am indebted to my assistant and secretary, Mr.
W. C. Unwin, for the care he has bestowed on reading
the proofs and preparing the illustrations. And in con-
clusion, I may express the wish that the present volume
may be found as useful and acceptable to a numerous body
of readers as I believe its predecessor has already proved
itself.

CONTENTS.

PART I.

EXPERIMENTAL HESEABCHE&

Kbsbabchbs on thb Besistakgb of Ctundbical Wbouoht Ibon

yS88KL3 TO 0OLLAF8B.

Face

Apparatus employed t . • . . . 1

Experiments on the resistance of tabes to collapse ' . .7

Lap and bntt joints , » . . . .15

Steel flue . . . , . . . .21

Elliptical tobes ....... 24

Besistance to internal pressore . . . .26

Generalisation of the results • . . . .28

Finctical application to constmction of the resolts . .41

BiSBABOHXS OH THE BbSISTAKOS OF 6lA8B GlOBBS AKD CtIJNDBRS TO
OOI.LAP8B FSOK EXTBSNAL FrESSUBB; AND OH THB TbHSILB AHD
CoifPBBSfllYE StBEHOTH OF TABIOUB EilHDB OF GuUSfl.

Gomposition of the Tarions kinds of glass .

Specific graTitj .......

Tenadtj of glass .

Besistance of glass to crushing ....

Besistance of glass globes and cylinders to internal pressure
Besistance of glass globes and cylinders to an external pressure
Beductlon of the preceding results

46
49
60
53
63
74
86

xiv

CONTENTS.

Besearghbs on the Tbnsile Stbength ov Wbouoht Ibon at various

Tempesatubes.

Page

Apparatus employed . . . . . .96

Experiments on boiler plate

on rivet iron .
on repeated fracture
Discussion of the elongations

100
114
125
127

IV.

On the Comparative Value of various Kinds of Stone, as ex-
hibited BT THEiB Powers of besisting Compbession.

Experiments on Yorkshire sandstones

on granite, granwacke, &c.
on the absorption of water
„ by others

General summary

»>

»♦

131
134
137
139
143

PART n.

LECTUEE 1.

On Fopulab Education.

Elementary teaching and physical training . • . 147

From the age of five to ten years . . . . . 150

Education during the period between the age of ten and fourteen . 151

Adult education from the age of fourteen to twenty . .154

LECTURE n.
On the Machinebt employed in Aobiculture.

Early Eastern agriculture . •

American agriculture . •

Arthur Young and Bobert Bakewell
The plough • • •

Steam machinery •
Beapinfl^ machines •

162
164
165
167
169
176

t«MM ■ ■ m0*\

CONTENTS*

LECTUBE m.

OV THB RI8B or CiTIL AND MSCRAMICAL EnOIMSSBIKG, AND ITS
FROGBE88 TO THE PBE8ENT CeNTUBT.

Pag«

. 187

. 192

. 196

. 200

Condition of constructiye art down to the seventeenth century
The steam-engine .......

Millwork from 1700 to 1800 . . . . .

Engineering during the latter half of the eighteenth centary

The steam-engine, and the results of its employment since the time

of Watt .•♦..,..

The cotton trade .......

The iron trade .......

203
206
207

LECTURE IV.
On the Pboobess ot Citil and Meohanioal Enoineebinq duboto

THE FBESBNT CeNTUBT.

Influence of trade unions
Bennie and Telford
Steam nayigation .
Iron shipbuilding .
Iron houses .
Prime movers
Millwork
Bailways

211
215
219
223
225
228
234
238

LECTURE V.
On THE CONSTBUOTION 07 IbON 8hIP8.

The strength of the ship considered en masse
Weakness of the upper deck on the present construction
Proportion of deck section to keel .
Riveted joints .....

Proposed modifications ....

244
247
250
259
265

LECTURE VL

On the Constbuction or Iron Ybssbls exoeeoino Thbee Hcndbed

Feet in Length.

Lloyd's regulations

The general principle of construction

Water tight bulkheads

Details of the cellular bottom

War vessels

268
271
276
276
280

XVI

CONTENTS.

LECTUBE Vn.
On Wbouoht Iron Tubulab Cranbs.

TweWe ton cranes for Eeyham
Sixty ton crane for Eeyham
Steam cranes
Bailway trayelling cranes .

Page
282

290

295

297

LECTURE Vm.
On the Properties of Steam, its MANAOBsrENT and Apflioation.

New principles in the constmction of boilers
Strength as affected by length
Strength as affegted by diameter
Strength as affected by thickness of plates
Density of steam •
The law of expansion

299
301
303
304
306
313

APPENDICES.

I. On the resistance of Basalt to crashing
II. Mr. Grantham's Tiews on the strength of iron ships

III. Letters to *' The Times " on iron ship building .

. 315
. 316

.. 318

Index

. 327

/■

LIST OF PLATES.

L Elevation of Ezperiiientju* Apparatus . to face page 3

IL Pkoposbd Impboyembnts • ... „ 45

IIL Apparatus vob Expbriiobiits oh the Tbksilb

Strehoth of Iron „ ^8

IT. Fractured Surfaces of Iron „ 114

PART I.

EXPERIMENTAL RESEARCHES-

I. EEBEARCHES ON THE BESISTANCE OP CYLINDRICAL
VESSELS OP WROUGHT IRON TO COLLAPSE.

(Reprinted from the Transactions of the Rojal Society, 1658.)

The following experiments were undertaken at the joint
request of the Hoyal Society and the British Association
for the Advancement of Science. Their object is to de-
termine the laws which govern the strength of cylindrical
vessels exposed to a uniform external force, and their
immediate practical appHcation in proportioning more ac-
curately the flues of boilers for raising steam, which have
hitherto been constructed on merely empirical data.

It is well known that the immense extension of the
application of steam power, and the consequent induce-
ment to economise as far as possible the fuel necessary
for its production, together with the growing tendency to
employ the expansive principle, has caused a general in-
crease of the working pressure from 10 lbs. to 50 lbs., and
even in some cases to 150 lbs. on the square inch. Unfor**

•I

ON THE BE8ISTANCE OF

tunately^ however, our knowledge of the principles of
construction has not kept pace with our desire to econo-
mise, and hence the change has been accompanied hj an
increase of dangerous and fatal accidents from boiler ex-
plosions. Investigation has frequently shown these
lamentable catastrophes to have arisen from ignorance of
the immense elastic power of steam, and from a want of
knowledge of the forms of construction best calculated to
retain an agent of such potent force; and as explosions
become more frequent in proportion as the pressure is
increased, it is the more necessary to inquire into the
causes of such disasters, and to apply such remedies as
may effectually prevent them.

In order to save space, and to increase the generative
powers of boilers, internal fines and tubes have been ge-
nerally adopted, and that without sufficient attention to
proportioning their diameter, length, and thickness of
plates, so as to ensure safety on the one hand, and eco-
nomy of material in its judicious distribution on the other.
Hitherto it has been considered an undisputed axiom
among practical engineers, that a cylindrical tube, such as
a boiler-flue, when subjected to a uniform external pres-
sure, was equally strong in every part, and that the length
did not affect the strength of a tube so placed. But
although this rule may be true when applied to tubes of
indefinite length, or to tubes unsupported by rigid rings
at the extremities, it is very far from true where the
lengths are restricted within certain apparently constant
limits, and where the ends are securely fastened in frames,
which prevent their yielding to an external force.

In some experimental tests to prove the efficiency of
some large boilers, the author had some misgivings as to
the strength of the internal flues to resist a force tending
to collapse them. In these experiments it was found that
flues of 35 feet long were distorted with considerably less

TUBES TO COLLAPSE, 3

force than others of a similar construction 25 feet long.
This anomalous result led to further inquiry, which being
far from satisfactory, the present series of experiments
were instituted, with, it is believed, very conclusive
results.

In order to have every facility for conducting these
experiments, application was made to the Directors of
the North-Eastem Division of the London and North-
western Bailway, for permission to conduct them under
their large octagonal engine-house at Longsight, near
Manchester, where the necessary pumps and cranes were
at hand. To this request the Directors gave their cordial
assent, and in this position I had the benefit of the sug-
gestions and experience of Mr. J. Ramsbottom, the
Company's engineer, and also the constant attendance of
Mr. R. B. Longridge, the engineer, and chief inspector to
the Association for the Prevention of Boiler Explosions.
To both those gentlemen I tender my best acknowledg-
ments for the able and efficient assistance I have received
from them during the whole time occupied in conducting
the experiments*

To attain the objects of the experiments in a satisfactory
manner, it was necessary that the apparatus should be of
great strength and of dimensions capable of receiving
tubes of considerable length and diameter. For this pur-
pose a cast-iron cylinder was prepared, 8 feet in length,
28 inches in diameter, and 2 inches thick of metal, for the
reception of the tubes to be experimented upon. This
cylinder, C, Plate I., was placed upon some balks
of timber, in one of the locomotive pits, immediately
under the shear legs A, A, for the convenience of lifting
and replacing the heavy cover of the cylinder, which had
to be removed at the close of each experiment. A small
pipe, a, a, connected the force-pump, B, with the interior
of the cylinder; and another, J, J, communicated with

B 2

4 ON THE EE8I8TANCE OP

the steam-pressure gauges at c, wUcli exhibited the pres-
Buie in the cylinder during the experiment in lbs. per
eqnare inch: to ensure accuracy two gauges were em-
ployed, one of Schaeffer's and the other of Smith's con-
struction, and the indioatiooB of these were checked by an
accurate safety-valve, d. A small cock, e, served to let
off the air contmned in the cylinder when e

Fig. 1. — Verlicai Section,

TUBES TO COLLAPSE. 5

Fig. 1 is a section of the large cylinder. The top and
bottom covers, f and g^ were made of strength propor-
tionate to that of the cylinder, to which they were secured
by 1-inch bolts placed 3 inches apart. In the bottom
cover, gy a hole was drilled, to receive the rod and screw-
nut A, which supported the tube D to be experimented
upon; and through the top passed a 2^-inch pipe, m, in-
serted in the cast-iron end of the tube D. On the end -of
this pipe was a large nut, which screwed down upon an
indian-rubber washer on the cover of the cylinder, so as
to close the opening round the pipe and make it water-
tight. The object of this pipe was to allow the air from
the interior of the tube D to escape during the collapse,
and so to place it, as nearly as possible, under the same
circumstances as the flue of a boiler.

The whole of the experiments were efiected by means
of the hydraulic pump, by which water was forced through
the pipe a a into the cylinder C ; thus driving the air in a
highly compressed state to the upper part of the cylinder,
whence, when a very high pressure was requbed, it was
deemed advisable to let it escape by the cock ^, and to
effect rupture through the medium of water only. In
both these cases a perfectly uniform pressure was ensured
upon every part of the tube to be collapsed.

These preparations having been made, and the pressure-
gauges carefully adjusted, the experiments proceeded as
shown in the following Tables.

The first experiment was upon a tube 4 inches in dia**
meter, and 1 foot 7 inches long between the cast-iron ends,
to which it was riveted securely and brazed. It was com-
posed, as in the other experiments, of a single thin plate,
bent to the required form upon a mandril, and riveted,
and also brazed to prevent leakage into the interior. This
tube having been fixed to the cylinder covers in the
manner described above, the pump was applied and a

B 3

6 ON THE BESI8TANCE OF

gradually-increasing force given to its exterior surface^
until its powers of resistance were overcome. During the
experiments the precaution of allowing the air to escape
at high pressures was found absolutely necessary^ as the
tubes generally collapsed with an explosion of the sud-
denly-compressed air in the tube D, fig. 1^ accompanied
by a loud report as it made its escape by the pipe m^
These explosions give pretty correct indications of what
takes place when the internal flues of boilers collapse.

It has long been a desideratum to determine some law
by which the engineer could calculate the proportionate
strength of the internal flues. Hitherto we have acted
upon the principle that the cylindrical flues, as ordinarily
constructed, were considerably stronger than the outer
shell ; but this opinion has in reality no foundation in ex-
periment, excepting only uncertain deductions from occa-
sional explosions and the failure of vessels under high
pressures in circumstances of a very variable and doubtful
character. There have been no definite rules to guide us
hitherto in proportioning the diameter, length, and thick-
ness of plates of the flues, so as to correspond with the
strength of the boiler; and even in cases where explosions
have taken place from collapse, we have, it is to be feared,
too frequently mistaken the actual cause, in consequence'
of the d6bris covering the site, and the force which has
torn to pieces the outer shell. The anomalous position
in which these constructions are placed has greatly re-
tarded the application of science to their improvement,
and there appears, in fact, to be no rule known by which
to attain uniformity of strength between those parts of a
boiler exposed to an internal tensile, and those exposed to
an external compressive force.

To supply this want, and to remedy certain anomalous
results arising from defective forms of construction, it
appeared desirable that these vessels should be subjected

TUBES TO COLLAPSE. 7

to direct experiment, and the Laws of Resistance as far
as possible ascertained, and the necessary formula deduced
for the future guidance of the practical mechanic and
engineer. These objects have, it is believed, been
attained by the results developed in the experiments
enumerated in the following Tables.

EXFSBIMENTS.

Resistance of Tubes to Collapse.

In these experiments the tubes were composed of
plates of uniform thickness, and of the form and size
shown by the figures in the column of remarks. The
form after collapse is also indicated by the woodcuts.

On consulting Table I., it appears that tubes of the
same diameter and the same thickness of plates vary
in strength when of different lengths. The tubes of
19 inches and those of 40 inches differ widely in their
powers of resistance. Comparing the results of Experi-
ments I and 2 with those of Experiments 3 and 4, we find
that the latter, while of twice the length, bear less than
half the pressure. Comparing these with Experiment 5,
we find that tube E, 5 feet long or three times as long as
A and B, exhibits only about one-third of their mean
strength. Similarly, E, which is -| the length of D, bears
only about ^ the pressure.

Tube F, Experiment 6, may be considered as composed
of three distinct tubes, each 1 foot 7 inches long. It was
made with two perfectly rigid rings, soldered to the out-
side of the tube to keep it in form and prevent collapse at
those points. The result of this alteration was to increase
the strength of the tube threefold, as is evident on com-
paring it with tube E.

Table II. gives indications of the same law of re-
sistance as the last. It will be observed that the tubes

B 4

ON THE BE3ISTANCB OP

TDBE8 TO COLLAPSE.

* On removing the tubes Q, H, it wtu foanil, that owing to the thinness
of the metal, the cast-iron enda of hoth had been fractured, eaosing collapse,
perhaps, before the onter shell had attained its maximnm resistance.

f Tnbe M bad an iron rod down its axis to prevent the ends approaching
each otiier dnring collapse ; a tin ring bad also been left in by mistake,
which acconnis dx the incTeased ptessnre required to prodnce collapse.

10 ON THE EESISTANCE OF

being screwed to the covers of the cylinder, were to some
extent in a state of tension, owing to the necessity of
having to screw up the air-tube tight in order to prevent
leakage. This, with the weakness of the ends of the first
two tubes, will account for the discrepancies in the Table.
Making allowances on this ground, and taking the mean
of the experiments, we arrive at the conclusion that the
results approximate closely to the law that the strengths
are inversely as the length ; and this, it will be observed,
is the result arrived at in the comparison of the 4-inch
tubes.

Thus the mean strength of the tubes, 30 inches long,
experiments G, H, K, L, is 53 lbs. per square inch.
Now by the above inverse proportion, we may calculate
from this the strength of a tube 59 inches long; thus,

59 : 30:: 52 : ar=27i

the result being 32 in the above Table, Experiment 9, a
difference of 5 lbs. only.

This law receives remarkable confirmation from Ex-
periment 6 on tube F. This tube had, as already ex-
plained, two rigid cast-iron rings firmly soldered to it so
as to divide its length into three equal parts. The result
was to increase the strength threefold, or, in other words,
to make it equal in strength to a tube of one-third the
length.

The next series of tubes submitted to experiment were
8 inches in diameter, and of the same thickness as the
preceding. In these experiments it will be seen that the
same law in respect of the length prevails, and is perhaps
more strikingly exemplified than in either of the preceding
series. Perhaps from their larger size these tubes were
less affected by defects of workmanship. Like the last,
they had an outlet for the escape of the air, and collapsed
with loud reports.

TUBES TO COLLAPSE.

^ ^ ^'

pi*

S S 3

i i ?

s s s

-Biirai

2 2 2

ii 6 Bi

12 ON THE RESISTANCE OP

On comparing the above results^ it will be found that
there is a near approximation to the strengths being
inversely as the lengths. Taking the strength of the first
tube^ 30 inches long, and calculating the force necessary
to collapse the 39 and 40-inch tubes, we have, by calcula-
tion,

39 : 30 :: 39 : a:=a30 and 40 : 30 :: 39 : ar=29-25 ;

the difference from the result in the Tables being 2 lbs. in
the one case and 1^ lb. in the other.

The following results on 10-inch tubes are also re-
markably consistent with the above law.

Both tubes gave way, as in the preceding experiments,
with a loud report. Comparing them, we have 50 : 30 : :
33 : :r=19*8 ; and by experiment (16) we have 19 lbs.

Equally strong evidence in confirmation of the law re-
specting the lengths, will be found in the Table of 12-inch
tubes. The increase of diameter, without any change in
the thickness of metal, does not affect it. On the con-
trary, this principle of resistance, in the case of tubes
with unyielding ends and open for the escape of the con-
tained air, holds true, uniformly, throughout the whole
of the experiments on 4, 6, 8, 10, and 12-inch tubes, as
nearly as could be expected when due allowance is made
for variations in the rigidity and thickness of the plates,
imperfections in the workmanship, and difference in the
tension of the sides.

Taking Experiment 20 as correct, we have for the
collapsing pressure of a similar tube, 5 feet long, 60: 30: :
22::r=ll, or 1*5 lb. less than Experiment 19. Simi-
larly, 58^ : 30::22 : ar=ll'2, or 0*2 lb. more than in
Experiment 18. From these results we may reasonably
conclude that the law affecting the strength of tubes is,
other things being the same, that the collapsing pressure
varies inversely as the length.

TUBES TO COLLAPSE.

^ m

||3*

: :

i ?

s s

S 2

S S

S ai

ifi

= I I

' i 1 i

f S 8

" ^ w

2 2 g

«J H >;

TUBES TO COLLAPSE.

The tube S, when compared with the 6-Inch tubes only
one-half the length, required a pressure of less than one-
fourth to cause collapse. This apparently low pressure,
though at first sight anomalous, is confirmed by the re-
sult of Experiment 19. Similarly, comparing tubes C and
D, Table L, with tubes and P, Table III., we havej

Length* Diameter. Pressure.
• • 39 • • 4 • . 65
. . 39 . . 8 . • 31-5;

CandD
OandP

Fig. 2.

that is, whilst the diameters are to one another as 1 : 2,
the pressures of collapse are as 65 : 31*5, or as 2 : 1 very
nearly. These comparisons, which might be continued,
evidently point to a law afiecting the diameters similar to
that of the lengths.

In order to ascertain the difierent powers of resistance
of tubes composed of thick plates and of difierent dia<
meters, a strong tube only 9 inches in diameter, and
formed of a plate :^inch thick, was constructed, to match
and compare with another tube, also of ^-inch plate, and
18J-inches in diameter. The 9-inch tube was, however,
found to be too strong for the retain-
ing powers of the cylinder, which it
would not have been safe to have
trusted above 500 lbs, per square inch.
Finding the strength of the small tube
too great for the containing vessel, two
new tubes were made, one with a lap-
joint as at A in the annexed sketch,
and another with a butt-joint as at B.
These tubes were made of plates -|^th of
an inch thick, the object of the difier-
ence being two-fold \-^rsty to ascertain
to what extent the strength of the tube
was reduced by the lap-joint ; and
secondly y to compare with the tube 18 J inches in diameter.

ON THE EE8ISTANCE OP

C -^ -brail

in'ix^d-mi So « go

's.diTiOj n « D S

jouni»ij i * « n

'ttamiaiqx ?* ?■ T* -

TUBES TO COLLAPSE. 17

and double the thickness of plates. In the construction
of boilers the lap-joint is almost invariably in use ; and
it must at once appear obvious that any such departure
from the true circle in cylindrical tubes must impair their
powers of resistance to external pressure.

The tube Y, Experiment 23, was made with a lap-joint,
which caused it to deviate from a true circle in form, to
the extent of nearly a qtiarter of an inch, the double
thickness of the plates. In the tube Z, the cylindrical
form was better maintained by the butt-joint, and this
difference, apparently so small, had a serious effect upon
the resisting powers of the tube. According to the re-
sults in the Table, there was a loss of more than one-third
of the strength in the tube with the lap<joint, the ratio
being 69*3 : 100, or 7 : 10 nearly. These facts are con-
clusive in showing the necessity of adhering in these
constructions to the true cylindrical form.

The foregoing experiments were instituted for the
purpose of ascertaining the resistance of tubes to collapse,
when the ends were securely fixed to unyielding discs (as
is the case with the flues of a boiler), and rigidly kept
apart to prevent their approaching one another. In this
position, the tubes, when submitted to severe collapsing
pressures, weie to some extent in a state of tension, and
in some few cases, when collapse took place, the sides
were torn from the cast-iron discs.

The results obtained from tubes of this construction
have already been recorded, but we have yet to ascertain
to what extent tubes of the same size and form follow the
same laws in their resistance to external pressure when
their ends are left free to approach each other. To solve
this question two tubes were made, similar ta those pre-
viously experimented upon, of 8 inches diameter and 60
and 30 inches in length* In these tubes there was no
rigid bar down the centre, nor were they attached to the

ON THE BiSISTANCE OF

^ m

a s

1 5

s s

iJ.

CO «

s s

. i

^ S

TUBES TO COLLJlPSE.

20 ON THE RESISTANCE OP

cylinder covers ; they were simply placed in the cylinder,
and water pumped in, in the usual manner, until they
collapsed as given in Table VII. :-—

In the above experiments the tubes do not appear to
follow precisely the law of '* inversely as the length."
Had they done so, the tube BB should not have yielded
with a less pressure than 44 lbs. on the square inch. It
IS, however, impossible to manufacture these tubes truly
cylindrical, and hence it follows that slight variations
may very materially affect the ultimate strength of the
tube.

From three experiments on 4-inch tubes, we derive
data more in accordance with the law, as will be seen
in Table VIIL

In the above experiments, the second on tube DD is
lost, in consequence of the ends being fractured and the
water obtaining admission, so as to cause a counteracting
pressure in the interior. Experiment 29 agrees closely
with the law when compared with 27, its strength being
correctly double that of the latter. The 15-inch, al-
though not four times the strength of the 60-inch, exhibits
high resisting powers. It is probably difficult to recon-
cile these discrepancies; but we have in these experi-
ments sufficient data to show that these tubes also follow,
in their resistance to collapse, some function of the
length ; and it is important to observe, that we cannot in
practice introduce long tubes into constructions exposed
to external pressure, without making very considerable
aUbwance for their loss of strength.

In the earlier experiments the tubes were made of thin
wrought-iron plates ; but conceiving that it would be of
interest to examine how far the laws, which were found
to prevail with them, applied also to tubes of other
materials, three tubes were made of the following dimen-
sions: —

TUBES TO COLLAPSE.

GG. Iron flue, 15 inches in diameter : —

-«r-

Plates *125 inch thick.
Web (a a) '25 inch thick.
Bivets ^ inch, at 1^ inch apart.

HH. Steel flue, diameters 15^ and 15^ inches :

Ul% ^ 1 XT- » »,...^'

Tt'

••>.

Plates *125 inch thick.
Web (J b) -25 inch thick.
Bivets \ inch, at 1^ inch apart.

JJ. Iron flue, with overlap joints; diameters 14^ and

14J-J- inches : —

•

o
o
e
e
«

.- — !■■■■ ' .— . mm. m. .— ^O^.— — .

SB C6UW^€,

Plates '125 inch thick.
Ends *25 inch thick.
Length 5 feet.

Bivets \ inch, at 1^ inch apart.

c 3

ON THE BESISTANCE OF

Table IX. Resistance of Sted and Iron Flues,

Diameters.

Thickness.

GG.

inches.

l«en
incl

inch.

•125

HH.

15Axl5f
l4xl4i|

•125

JJ.

•125

Pressure of

collapse.

lbs. per sq. in.

150
220
125

Remarks.

Each had an internal
longitudinal stay be-
tween the ends.

The experiments on these tubes do not at first sight
appear to yield very satisfactory results. The first, GGr,
gave way with a pressure of 150 lbs. on the square inch,,
when it began to leak so much as to cause its removal
from the vessel, to replace some of the rivets which were
imperfect. After the necessary repairs, it was again sub-
jected to experiment, when it gave way with a force of
146 lbs., showing how much it had been injured by the
previous pressure. On comparing it with the mean re-
sults of all the other experiments, we find that it should
have borne about 300 lbs. : it evidently failed at the
rivets, and cannot be relied upon.

The next experimented upon was a steel tube, of the
same form and with similar rigid divisions to those of the
iron one. This sustained 220 lbs. on the square inch,
when it bulged in or collapsed in the middle division.

The last was a plain tube of similar plates of iron, 14-|
inches in diameter, but without ribs. This collapsed with
a pressure of 125 lbs. on the square inch; and this
agrees nearly with the preceding experiments, as will be
seen.

Comparing Experiments 32 and 33, it would appear
that the steel tube is not stronger than the iron ; but we
are not warranted in drawing general conclusions from a
single experiment.

TUBES TO COLLAPSE. 23

The next experiments were of a different charactery
upon tubes of an elliptical form. Table X. gives the
results.

The two experiments on cylindrical tubes sxe ap-
pended for comparison.

On comparing the elliptical tube "Bb with the cylin-
drical tube X, which are of the same length and thick-
ness of plates, and only about half a square inch different
in sectional area, we have for the collapsing pressure of
the former 127*5 lbs., and for that of the latter 420 lbs.,
where it will be observed there is a loss of about ^ths of
the strength, in consequence solely of the flattening of
the tube B^, or in other words, a cylindrical tube will
support nearly three times the pressure which would
collapse an elliptical tube of the same weight when
proportioned like tube Bft. A similar deficiency is
observable in tube A«, when compared with tube T.
The change of form, from the cylinder to the ellipse,
where the diameter was. reduced to 1^ inch in one direc-
-tion and extended as much in another, reduced the bearing
powers one-half. The comparative results obtained from
the experiments on the thick tube are different from those
on the thin one, the loss being much greater in the former
than in the latter^case, although the ratio of the diameters
is about the same. Allowance must, however, be made
for inaccuracies of construction, though we might reason-
ably have expected a nearer approximation in the ratios
of the deficiency of strength. From these facts, how-
ever, it is obvious that in every construction, where tubes
have to sustain a uniform external pressure > the cylindrical
is the only form to be relied upon, and any departure
from it is attended with danger.

ON THE KESISXANCE OP

• 1

i§

■n^Sli

1 P

■3;^

S 5

S =

s s

fi:

-vm

i s

HeJ

TUBES TO COLLAPSE.

^ ■. .

5U1

Jf^f

■*

■ s

26 ON THB BESISTANCE OF

Resistance of Tubes to Internal Pressure.

During the investigation on the comparative resisting
powers of tubes to collapse^ a question arose as to the
relative powers of cylindrical tubes to resist an internal
force acting uniformly over their surface. It has already
been demonstrated that the resistance of cylindrical
vessels to internal pressure varies inversely as the dia-
meters, but what effect the length may have upon the
strength has yet to be determined. We have already
seen that a cylindrical tube, when subjected to external
pressure, loses one-half its strength when the length is
doubled, and so on in other cases; hence arose the in-
quiry, what effect, if any, will an increase of length have
upon a tube exposed to internal pressure ? To solve this
problem, three tubes of precisely the same diameter and
thickness of plates, but of different lengths, were pre-
pared and submitted to experiment as seen in Table XI.

Considerable discrepancies occur in the experiments on
internal pressure, as in each case the tube gave way at
the riveted joint. Every precaution was taken, by care-
fully brazing them, to render them as nearly uniform in
strength as possible. The weakness of these joints was,
however, very apparent, and the results are in accordance
with those arrived at several years previously, when it
was found that the strengths of riveted plates were as the
numbers —

100, for the solid plate ;

70, for the double-riveted joint ;

66, for the single-riveted joint.

This constant failure at the joints renders the experi-
ments on internal pressure very unsatisfactory, as they
do not exhibit the ultimate strength of the plate, but only
the strength of the joint ; and as boilers invariably present

TUBES TO COLLAPSE. 27

joints, these facts are probably of some significance when
applied to them. On a careful examination of the
fractures, that of the tube F/* appeared the most perfect.
"Ee was not so well soldered, and burst by tearing off the
riyet-heads, and Dd was torn partly through the plates
and partly through the rivets; the plate of which this
tube was composed was, however, exceedingly brittle, and
broke like cast-iron. Tube Gff was ruptured in the same
way and in the same direction as the others ; the rivets
were torn through the plates, and the soldering (not very
sound) was ripped up for 10 inches along the joint : this
tube, as also the others, would have borne a greater pres-
sure had the joints been more perfect and of sounder
workmanship.

Comparing the tube Cc, 1 foot long, with the tube Ff,
4 feet long, and assuming the joints to be equally perfect
in each, it would appear that there is a slight loss of
stren&^th when the length is increased; and this afi^ain
suggests ihe question, dVthe rigid ends in short tfbes
increase the strength of the unsupported portion in pro-
portion to the length of the tube ? For example, let us
take two tubes of any given diameter, the one 10 feet and
the other 20 feet long ; it would appear, primd facie y that

it was much easier to force the long tube into the form of
a barrel, as at a, than it would be to produce the same

28 ON THE EESISTANCE OF

form in the shorter tube^ as at & ; in an elastic material^
such as an indian-rubber tube^ the extension would cer-
tainly take place at the centre, where the particles possess
diminished resistance^ arising from their respective distances
from the ends or points of supports

To ascertain how far this view is correct, two leaden
pipes were prepared of 3 inches diameter, and of the
lengths of I foot 2^ inches, and 2 feet 7 inches respec-
tively, and these were submitted to the experimental
tests in Table XII., : —

The tube H^ ruptured at the thin part of the metal, the
water bursting through a narrow slit ; 3j ruptured simi-
larly ; and on measuring the expanded circumferences at
the broadest part, it was found that the metal of the
former had elongated 1^ inch^ and that of the latter 1^
inch.

These experiments seem to show pretty conclusively,
that the length has very slight influence on the resisting
powers of tubes of wrought iron to internal pressure.
Beyond the limit of one or two feet in length, it appears
to affect the strength so slightly^ that it may be almost
entirely disregarded in practice.

GENERALISATION OF THE RESULTS OF THE EXPERI-
MENTS.

In the reduction of the experiments^ I have, as on
former occasions, been ably assisted by my friend Mr.
Tate, whose sound philosophical views and high mathe-
matical attainments are, from his numerous publications,
so well known to the public. To that gentleman I am
indebted for many services, and among, others for an ela-
borate inquiry into the specific gravity and properties of
steam^ which I hope will be shortly forthcoming as a new
addition to our knowledge^ and that more particularly in

TUBES TO COLLAPSE.

^
^

I
I

CO 5

P.©
©I 'B

a
«>

I
s .

•? 3
^4

*qoa{ *bi

Ji»d -sqi

*8jn)dnj

JO »jn9i4Jj

In.
CO

*«aq30T
*998ai[3iqX

'saqaui

•saqdQ)

•OK

Oi«

'Urm

'>^

30 ON THE BESISTANCE OF

its application to the wants iCnd necessities of the present
high state of civilisation*

On this question I am personally gratified to find the
subject in such able hands, and aided by the industry,
care and perseverance of my own assistant, Mr. W. C.
Unwin, I entertain hopes of rendering the researches now
in progress of such a character as fully to justify the
application of the word useful^ which of all others is prob-
ably the best calculated to express the true value of these
investigations.

FormvJxB of Strength relative to Cylindrical Tubes.

The strain which the material of a cylindrical vessel un-
dergoes, when a uniformly-distributed external pressure is
applied to it, is very difierent from the strain produced when
the pressure acts internally. In the latter case the material
is equally extended throughout all its parts, and its cylin-
drical form is preserved at all stages of the pressure, with
the exception of a small portion closely bordering upon
the inflexible plates closing the extremities. The tube

under a high internal pressure
will assume the form represented
in the annexed diagram, and the
relation of the force of rupture
to that of resistance will be ap-
proximately expressed by

p=^*> (•)

where P represents the pressure requisite to produce rup-
ture, E the ultimate resistance of the material to extension,
D the diameter of the tube, and k its thickness ; whereas
in the former case, the material, being compressed, be-
comes crumpled in longitudinal lines near the middle ; the
tube loses its original cylindrical shape at and near to that

TUBES TO COLLAPSE. 31

part, whilst the portions towards the extremities being
supported by the inflexible end plates, retain, or nearly
retain, their original form ; so that, in fact, the material
TirtuaUy resisting compression is the comparatively small
portion at and near the middle, and which, to a certain
extent, is independent of the length of the tube, whilst
the pressure producing the compression is always ap-
proximately proportional to the longitudinal section. Now
let us assume for these tubes, —

P^ = the external pressure of the fluid in lbs. to produce
rupture or collapse ;

P = this pressure per square inch ;

B = the resistance of the material to compression or to
crumpling;

L = the length of the tube in feet;

D = the diameter of the tube in inches ;

k = the thickness of the plates in inches ;

p == the pressure P reduced to unity of length and dia-
meter, or = PLD ;

C, a, constants to be determined from the data supplied
by the experimente.

Since P', the total pressure on the tube, varies directly
as the longitudinal section, that is, as the product of. the
length by the diameter, we have

F=C^P.L.D.

Now it has been determined by experiment, that the
resistance of thin iron plates to a force tending to crush
them, or rather to a force tending to crumple them, varies
directly as a certain power of their thickness, the number
indicating tiie power lying between 2 and 3 ; hence we
assume.

32 ON THE RESISTANCE OF

but when rupture takes place, P'=R, and

• • -^ LD ^^

For tubes of the same thickness, we readily derive from

this equality,

P.L.D.=P^.L^.D,; .... (3)

that is, the continued product of the pressure, the length
and the diameter is constant ; or in other words, for tubes
having the same thickness, the pressures of collapse reduced
to unity of length and diameter {p) are equal to one
another.

To determine the values of the constants a and C in
(2), we have

But in order to embrace a range of experiments by
taking the mean of their results, we have, putting p for
the value of P, when the tube is reduced to unity of
length and to unity of diameter.

P. %r

log£-log£,. .^.

'■■ logA-logA/ • • • W

and simikrly, we find

c=t' (')

A glance at the results of the experiments recorded in
Tables I. II. III. IV. V., where the thickness of the
plates composing the tubes is the same, is sufficient to
show, — 1st, that the strength of the tubes varies nearly

TUBES TO COLLAPSE.

inversely as their lengths ; 2ndly, that the strength also
varies nearly inversely as the diameters. The following
reduction of these experiments will not only render these
laws apparent^ but will also show that in tubes of the
same thickness the strength varies inversely as the pro-
duct of their lengths by their diameters^ or what amounts
to the same thing, that PLD ( =p) is nearly a constant
quantity.

Reduction of the Results of the Experiments on the Col-*
lapse of Sheet-iron Tubes '043 inch thick y to unify of
length and diameter.

Experiments 1, 2 and 6, were performed on tubes of
the same length and diameter, and also Experiment^
7, 10 and II; hence we have for the mean values of P, — »

Mean value of P from Experiments, 1, 2 and 6

170 + 137 + 140 ,^^
3 -149.

Mean value of P from Experiments 7, 10 and 11

48 + 52 + 65 ^^

A'inch Tubes.

No. of
Experiment.

Diameter in
Incites.

Length in

Feet.

Pressure

of Collapse

in lbs.

P.L.

Pressure

rednced

to Unity

OfL.

P.D.

Pressure

reduced

to Unity

OfD.

Pr^;ure

reduced to

Unity of

L and D.

1,2,6
3

5
27
29

1 T

31
5

5
2i

149
65
65
43
47
93

232-5
216-6
205-8
215*8
2350
232-5

596
260
260
172
188
872

930-0
866*4
823-2
8600
940-0
930-0

Mean value of o
D

6) 5349 6
\ 8915

ON THE RESISTANCE OF

The approximation of the numbers to one another in
columns 6 and 7 shows how very nearly the strength
varies inversely as the lengths. This observation applies
with equal exactness to all the reductions which follow.

6-uich Tubes,

No. of
Experiment.

P. L.

P.D.

P-

7, 10, 11
9

6
6

^
4

65
32

137-5
157-3

330
192

825
944

Mean value ofp
B'inch Tubes.

2) 1769
884*5

No. of
Experinaent.

P.L.

P.D.

P-

97-5

312

7800

104-0

256

832-0

103-8

248

826-4

Mean value ofp
IQ-inch Tubes,

3) 2438-4
812-8

No. of
Experiment.

P.L.

P.D.

/»•

16
17

10
10

41
2I

79-1
90-0

190
360

791
900

Mean value ofp

2) 1691
845-5

A comparison of the numbers in the sixth columns of
the above Tables with the numbers given by the experi-
ments on tubes of the same length, clearly shows that the
strength varies very nearly in the inverse ratio of the
diameters; and, moreover, since the mean values ofp for the
diflferent sets of tubes nearly coincide with one another.

TUBES TO COLLAPSE.

we infer that the strength varies inversely as the product
of the length by the diameter^ or that p = PLD = a constant.

12-iRcA Tuhea,

No. of ,
Experiment.

P. L.

P.D.

18
19
20

12-2

4ii
5

110
12-5
22-0

53-6
62-5
550

1S3^2
1500
2640

654

750
660

Mean value of/?

3) S064
•88

Here the mean value of p is somewhat below the value
determined from the other tubes. This discrepancy is no
doubt owing to the difficulty there is in maintaining such
thin tubes of large diameter exactly in the cylindrical
form. This circumstance seems to suggest that a small
correction, depending on the ratio of the diameter of the
tube to its thickness, may be requisite to render formula
(2.) mathematically exact. This correction will assume

the form of — E x -^, where the constant E remains to be

determined from the data of the experiments.

Mean value of p derived from the foregoing results,
jr>=^{891-6 + 884-5 + 812-8 + 845-5 H-688} = 824.

Reduction of the Results of Experiments 22, 24, 33 on
the Collapse of Sheet-iron tubes to unity of length and
diameter.

No. of
Experiment.

k
Thickness.

P-

22
24
33

18|

14|

•25
•14
•125

420
378
125

40,030

10,495

9,140

D 2

36 ON THE KE8ISTANCE OF

To find the Value of the Constants a and C in the General

Formula.

In equality (4), taking /?= 40,030, A=-25, ;?,=820,

A, = '043; we get

lo g 40,030 ^.log 820

"*" log -25 -log -043 -^^^'

Similarly, taking ;?;= 40,030, A ='25, ;?,=9140, and

A^ = *125; we get

_ log 40,030 — log 9 1 40
'*""~log-25-log-125 -2-14;

and taking j9^ 10,495, A=*14, j9^ = 820,^^ = "043; we get

log 10,495 -log 820
*- log -14 -log -043 --^^^^

and taking the mean of these values, we get a =2*19.
For the value of the constant G, we have from (5),

C=f;=;^j|^ = 806,300,

Substituting these values in (2.), we get

P=:806,300x^, • . . . (6)

which is the general formula for calculating the strength
of wrought-iron tubes subjected to external pressure*,
within the limits indicated by the experiments; tUat is,
provided their length is not less than 1*5 foot, and not

* Bj taking 2 instead of 2*19 for the index of A, this formula becomes

P=806,300x-^, (a)

whence the value of P, the collapsing pressure maj be readily calculated
by ordinary arithmetic.

For thick tubes of considerable diameter and length, this formula may
be regarded as sufficiently exact for practical purposes.

For example, let A» J inch, L= 10 feet, D»36 inches ; then

P=806,300 X ,^0^ = 560 lbs.
10 X 36

By formula (6), ;- P=l-5265 + 2-l9 log 50 - log 3 60 « 502 lbs.

It wUl be observed that these results do not differ widely from each other.

TUBES TO COLLAPSE.

greater probably than 10 feet. For greater lengths the
formula gives the collapsing pressure somewhat too low^
although the experiments on flues 30 feet long, to be
adverted to hereafter, show that up to that point the
variations from the theoretical collapsing pressure does
not exceed one-fourth.

In order to facilitate calculation, formula (6) may be
written,

log P= 1-5265 + 2-19 log lOOA-log (LD);

and when A=^043, by an obvious transformation, we have

820

P =

L.D'

The following Table will show how nearly formula (6)
represents the results of the experiments on the different
classes of tubes.

No. of
Experiment.

Diameter.

Inches.

Length.
Feet.

Thickneis.
Inches.

By Experi-
ment in Ibi.

ByFormula
(6.

Propor-
cionalError
by Formula.

2
5

7, 10, 11
14
16
19

8
10
12
18|

9
14f

5
2*

•043
•043
•043
•043
•043
•043
•250
•140
•126

137

12*5
420
378
125

h'tO
41
547
31-6
197
13-6

407

392

116

-So

So far as regards practical purposes, this formula ap-
pears to possess every desirable precision. As already
anticipated, the results derived from the thin 12-inch
tubes present the greatest deviation. The value of P,
derived from the following formula, gives a still closer
approximation to the results of the experiments, viz. —

P = 806,300 x-A-.- -002 X

P 3

*•

ON THE EESISTANCE OF

It is highly desirable that we should verify the law
P.L.D = P^,Ly.D^, as applied to thick tubes. Now, we
know the value of a independently of these experiments,
for its value, as determined above, closely approximates
to the value derived from the experiments on the com-
pression of sheet-iron plates. Let us, therefore, reduce
the collapsing pressure of these plates to unity of thick-
ness, with the view of ascertaining the law of variation
of pressure as regards length and diameter.

Let P be the pressure of collapse of a tube h inches thick,
and P' the pressure when the tube is '1 inch thick ; then

F /-IN*

P^UJ'

and

log P'=: log P~2-19 log (lOA).

Reducing the values of P by this formula, we derive
the following results: —

No. of
Experiment.

D.
Diameter.

L.
Length.

Thickness

Pressure.

P', or Value

of P reduced

to Unity of

Thiclcness,

▼is. 1.

Value of

P'. Lr. D.

•043

273

5400

18j

•250

420

5400

3^5

•140

378

190

5300

14f

•125

125

5600

The remarkable approximation of the numbers in the
last column to one another, distinctly establishes the law
(P.L.D=P^.L^.D^) in relation to tubes composed of
thick plates.

Deduction from the Results of the Experiments on the

Collapse of Elliptical Tubes,

By comparing the result of Experiment (34) on the

TUBES TO COLLAPSE. 39

elliptical tube with the result of the experiments on the
cjlindrical tubes^ we find that the general formula (6)
will apply approximately to elliptical tubes^ by sub-
stituting for D in that formula the diameter of the circle
of curvature touching the extremity of the minor axis.
Thus we have.

Diameter of the circle of curvature = , = — -—=20

nearly.

Now the pressure on this elliptical tube was 6*5 lbs.,
which reduced to unity of length and diameter, gives
650 lbs., which result nearly agrees with 688 lbs., the
mean pressure of the 12-inch tubes also reduced to unity
of length and diameter.

Although this deduction^ is based on merely one expe-
rimental result, yet it appears to be confirmed by the
following proposition* derived from mathematical analysis.

The pressure P per square inch, requisite to flatten
equal angular portions of a tube of variable curvature,
varies inversely as the diameters of curvature.

Hence it will be observed how very n^uch the strength
of a tube subjected to external pressure is deteriorated
by a deviation from the cylindrical form.

Strength of Cylindrical Tubes subjected to Internal

Pressure.

Taking the mean of the results of Experiments 36
and 39 on iron tubes, we have from formula

425 X 6
E= 2x'043 = ^^^^^Q ^^^^^y*

Hence we find

60,000A
^=—15 — » \J)

which gives the formula of strength of thin sheet-iron
tubes subjected to internal pressure.

D 4

40 ON THE RESISTANCE OF

Now the tenacity of boiler plates has been found to be
23 tons, or 51,520 lbs, per square inch ; hence it appears
that a considerable reduction of tenacity must be made
for the riveting of the plates. The ratio of reduction is
in this case f.

One remarkable fact distinctly established by these ex-
periments, is the comparative weakness of tubes subjected
to external pressure. If p be put for the internal pres-
sure per square inch at which a tube is ruptured, then
for tubes of the same thickness and diameter, we find
from (6) and (7) the following relation of strength : —

P" 13-44 -^A**

If L=2i and A=-043 theu ^= 7-77; that is to say,

in this case the tube subjected to internal pressure will
have about 7^ times the strength of a similar tube sub-
jected to external pressure. When

we find

L = 13-44A»^^

If A ='25, then we find L=i:3|^ feet nearly; that is, a
tube of this length and thickness will be equally strong
whether subjected to external or internal pressure.

Taking the mean of Experiments 41 and 42 on the
lead pipes, we have from formula (1),—

j,^370x3^22
2 X -25

which gives us the tenacity of lead per square inch.
Hence we find

P=^*. (S)

which gives the formula of strength of lead tubes sub-
jected to an internal pressure.

TUBES TO COLLAPSE. 41

Practical Application to Construction of the Results of the

Experiments.

Throughout the whole of the experiments enumerated
in the preceding pages^ it has been proved that the resist-
ance to collapse from a uniform external pressure^ in
cylindrical tubes, varies in the inverse ratio of the lengths.
This law has been tested to lengths not exceeding fifteen
diameters of the tube ; but the point at which it ceases
to hold true is as yet undetermined, and could only be
ascertained by a new and laborious series of experiments
on tubes of considerably greater length, in which the
strength of the material modifies the above law of resist-
ance to collapse. Such experiments are, doubtless, very
desirable ; but the vessels necessary for the purpose would
be most expensive, and the results already obtained ap-
pear to supply all the data necessary for calculating the
strengths and proportioning the material in all ordinary
cases.

If we take a boiler of the ordinary construction, 30
feet long and 7 feet in diameter, with one or more flues 3
feet or 3 feet 6 inches in diameter, we find that the cylin-
drical external shell is from three to four times stronger
in its powers of resistance to the force tending to burst
it, than the flues are to resist the same force tending to
collapse them. This being the case in boilers of ordinary
construction, it is not surprising that so many fatal acci-
dents should have occurred from the collapse of the
internal flues, followed inmiediately by the explosion and
rupture of the outer shell. To remedy these evils, and to
place the security of vessels so important to the commu-
nity upon a more certain basis, it is essential that every
part should be of uniform strength to resist the forces
brought to bear upon it. The equalisation of the powers
of resistance is the more important, as the increased

ON THE EESISTANCE OF

strength of the outer shell is absolutely of no yalue^ so
long as the internal flues remaiuj as at present^ liable to
be destroyed by collapse^ at a pressure of only one-third
of that required to burst the envelope which surrounds
them.

The following Table, deduced from my own experi-
ments, exhibits the safe working pressure, and the
bursting pressure of boilers of different diameters, calcu-
lated for an external shell of a thickness of |^ths of an
inch.

Diameter of Boiler.

Working Pressure.

Bursting Pressure.

ft. in.

lbs.

118

li'Si

3 6

101

607

88A

531

4 6

78}

472

70i

425

5 6

64|

386^

354

6 6

64i

326}

60j

303{

. /

7 6

283^
265j

•

44 '

■

8 6

41J

250

Taking from the above Table the strength of a boiler
7 feet in diameter, we find its bursting pressure to be 303
lbs. per square inch. For such a boiler the flues would
be ordinarily 3 feet in diameter, and of the same thickness
of plates as the shell ; and by the formula, log P= 1'5265
4-2*19 log lOOA— log(L.D.),we obtain for their collapsing
pressure, 87 lbs. per square inch. As, however, the for-
mula does not apply with strictness to tubes of such length,*
the actual collapsing pressure will be somewhat greater
than this. The immense excess of strength in the outer
shell is, however, sufficiently apparent ; the extra thick-
ness of boiler plate which causes it being so much material

TUBES TO COLLAPSE. 43

thrown away, adding nothing to the strength whilst the
flues remain in so dangerously weak a condition.

To meet this disparity of strength, the experiments
indicate the necessity of shorter flues, and one of them
shows how this may be obtained, practically and efliciently,
without interfering with the present construction of .boilers.
In Experiment 6, Table L, the tube F was divided into
three parts by two rigid rings soldered upon its exterior,
and its powers of resistance were thus increased in the
ratio of three to one ; virtually^ the length was reduced in
this ratio, and the strength was actually increased from
43 to 140 lbs. per square inch.

It is proposed to apply a similar construction to the flues
of boilers, to equalise their powers of resistance with those
of the outer shell, on the supposition that the law of de-
crease of strength holds true, within no great limits of
error, for tubes of much greater length than in the pre-
ceding experiments. That this conclusion is not empirical,
will be seen by the following experiments upon boilers of
full size, where it will be observed that the flues were
distorted with one-third the pressure required to rupture
the external shelL

These boilers were made for the North-Eastern Divi-
sion of the London and North-Western Railway Company,

Fig. 2.

and were respectively of 35 and 25 feet in length. They
were 7 feet in diameter, and composed of plates f ths of ah
inch thick. Each boiler had two cylindrical flues 3 feet
6 inches in diameter, and of the same thickness of plates

44 ON THE KESISTANCE OP

as the outer shell. They were fixed in the position shown

in the annexed diagram, and were intended to resist an

ordinary working pressure of only 40 lbs. upon the square

inch. In submitting them to the usual test of double

pressure, the flues of the first or longest boiler gave way

with 97 lbs. upon the square inch; and those of the shorter

Fig. 3. boiler required 127 lbs. to effect the same

^<=~v. distortion. With these large tubes a

/' \ complete collapse was not accomplished,

/f \ but the circular form, indicated by the

Ml; * »

\ \ dotted line, was distorted^ and the 'flue

\^ J became elliptical, as shown at h b*.

^''^X''^ The weakness of the flues in the above

experiments is so evident as to need no comment. To

* Beducing the above resalts to unity of length, which with flues of this
size should give a nearly constant quantity, we have —

D. L. P. P.L.

First boiler ... 42 35 97 3395

Second boiler . . 42 25 127 3175

The correspondence in the last column shows that these flues obey the law
of inversely as the lengths, very nearly, in their powers of resistance.

It may be well to test the accuracy of the formula which has been found
to apply to tubes of a length not greater than 10 feet, by determining from
it the strength of flues similar to the above, and comparing the results with
those derived from experiment.

Here, for the boiler 35 feet long, we have by formula

P= 806,300-^,

= 78 lbs. ; by experiment 97 lbs.

This difierence confirms the view already stated, that the formula for short
tubes does not apply strictly to tubes longer than 10 feet.
For the boiler 25 feet long, we have

P^109 lbs. ; by experiment 127 lbs.

A less difference between the experimental and calculated result, as wouli^
have been anticipated from the shorter length of the flue.

It will be observed, that even these experiments, upon full sized boilers,
are remarkably consistent, and offer no discrepancies which cannot be easily
explained consistently with the general formula.

o
o

TUBES TO COLLAPSE. 45

remedy it, it has been already stated, we need only resort
to a construction so simple, and yet so efTective, as to
meet at a small expense all the requirements of the case.

Figure 1, Plate TL, exhibits an ordinary boiler flue,
30 feet long and 2 feet 9 inches in diameter, with simple
lap-joints, as hitherto invariably constructed. To attain
nearly three times the strength of this, it will only be neces-
sary to introduce two or more strong, rigid, angle or X iron
ribs, as exhibited in figs. 2 and 3, at a, a. This arrange-
ment will not only remove all doubts as to the strength of
these flues, by bringing them within the limits to which
the formula applies with strictness, but will give to flues
30 feet long a strength equivalent to that of flues only 10
feet long, and make them uniform in their powers of re-
sistance with the other parts of the boiler.

The reduction of the strength of flues by the lap-joints
has already been stated ; the deviation from the true
cylindrical form which they cause, lessens, in some cases,
seriously the strength of the vessels, as may be seen in
Experiments 23 and 24, Table VI. Hence it is also pro-
posed that flues required to resist an external pressure
should be formed with double-riveted butt-Joints, with
longitudinal covering plates, as shown at b, b, b, fig. 3,
Plate II. It is believed that these alterations will secure
ample safety in these important constructions, and in this
trust they are commended to the attention of the engineer
and the public generally.

46 ON THE MECHANICAL PROPERTIES OF GLASS,

II.

researches on the resistance qf glass globes
and cylinders to collapse from external
pressure; and on the tensile and compressive
strength of various kinds of glass,*

(Reprinted from the Transactions of the Royal Society, 1859.)

The recently published experiments upon the collapse of
tubes of wrought iron^ led to results so novel and so
much at variance with the ordinary rules of practice, as
to exemplify anew the caution and diligence which are
requisite in investigating the physical laws of nature, in
order to arrive at just conclusions in regard to the pro-
perties of materials and their most effective distribution
for the purposes of construction.

In the experiments alluded to it was clearly shown that
the prevailing ideas of the strength of vessels subjected to
a uniform external force were erroneous, and at variance
with the laws of resistance to collapse under such circum-
stances ; whilst in practice the prevalence of error in this
matter had led to serious and sometimes fatal accidents,
arising out of the construction of vessels of inadequate
strength to sustain the pressures placed upon them. These
errors, it is hoped, need no longer be perpetuated, and in
order to give them as wide a circulation as possible, I
have — with the permission of the Council of the Royal

* These experiments were carried on in conjunction with T. Tate, Esq.,
bat are reprinted here on account of their connection with, and confirmation
of, the experiments in the preceding paper.

AND RESISTANCE OF GLASS VESSELS TO COLLAPSE. 47

Society— introduced the experiments in full and in such
a form as will give to the general reader a distinct idea
of the principles necessary to be observed in constructions
which involve considerations of such vast importance to
the practical engineer, in addition to the increased security
of life and property.

The experiments on wrought iron, therefore, indicated a
means of increasing the strength of boiler flues and other
vessels of that material, subjected to a collapsing force, to
any required amount ; and this was the immediate practical
application of the general law then discovered, that the
strength of cylindrical vessels exposed to a uniform ex-
ternal force varied inversely as the length between the
rigid ends.

The results deduced from the experiments on tubes
composed of riveted plates were so important as to sug-
gest further inquiry, under the same conditions of rupture,
but with other materials, differing in their physical pro-
perties from wrought iron. The joints in the tubes em-
ployed in those experiments were defects, the influence of
which might be determined by experiments upon homoge-
neous vessels. The ductile yielding character of wrought
iron suggested the extension of the experiments to hard
rigid materials, more capable of retaining their form under
pressure.

To fulfil the conditions thus sought for, glass was se-
lected for experiment, as a material differing totally in
character from wrought iron, and on that account well
fitted to supply data for extending our knowledge of
the laws of collapse. Of vitreous structure, rigid, elastic,
and brittle, and of low tenacity, it possessed the further ad-
vantage of being easily obtained and blown into homoge-
neous vessels of the required forms. But there were other
reasons which had weight in making this selection. Our
acquaintance with the strength of glass, in the various

48 ON THE MECHANICAL PROPEBTIES OP GLAS9,

forms in which it is employed in the arts and in scien-
tific research^ is ^ery limited^ and often as it is employed
in circumstances in which it is exposed to pressure^ few
attempts have been made to register observations of its
strength. Some researches on the density of steam at
high pressures^ now in progress, led to an examination
of the subject, and added, to other reasons for testing
its powers of resistance, the immediate necessity of know-
ing more of its properties before it could be trusted
in those experimental inquiries.

Our knowledge of the cohesive properties of glass is so
defective, that, to arrive at satisfactory and complete re-
sults, it was deemed advisable to ascertain by direct ex-
periment its tenacity, or resistance to a tensile strain, its
resistance to a crushing force, and, in the form of globes
and cylinders, to determine its resistance to an internal
bursting force, and to an external pressure tending to
produce rupture by collapse. The results of the expe-
riments upon glass globes and cylinders will, it is believed,
form decided contributions to our present knowledge rela-
tive to the laws which determine the strength of materials.
One remarkable result is that the law expressing the
resistance of glass cylinders to compression is precisely
similar to that which has been established for sheet-iron
cylinders.

The glass experimented upon was of three kinds, known
commercially as

Best Flint-glass,

Common Green Glass, and

Extra White Crown-glass.

The fiint-glass obtained from Messrs, Molineaux,
Webb, and Co., Manchester, was made of sand, oxide of
lead, and carbonate of potash, in the following propor-
tions : —

AND RESISTANCE OF GLASS VESSELS TO COLLAPSE. 49

Sand . . . • ^4 per cent
Bed oxide of lead • . 22 per cent

Carbonate of potash • 24 per cent

This glass is of a fine transparent character^ fusible^ and of
a high specific gravity^ due to the large per centage of lead
in its composition.

The green and crown-glass were obtained from Messrs.
Chance Brothers^ of Birmingham^ and were made of sand,
soda^ and lime^ in the following proportions: —

Common Green Glass.

Sand . • . . .100 parts.
Sulphate of soda • • .42 parts.
Carbonate of lime ... 45 parts.

•

This is a hard infusible glass of a green colour^ trans-
parent, but of a less density than the flint-glass.

White Crotcn-fflass,

Sand 100 parts.

Carbonate of soda • . • 38 parts.
Lime • • • • .11 parts.

A clear transparent glass, hard under the action of the
grindstone, and highly infusible.

The specific gravity of these different kinds of glass
varies greatly; the following Table gives the result of
several determinations : —

Specific Gravity of Glass.

Mean.
Best flint-glass . . 307871 o.n'zQo
Best flint-glass . • 30777 J "* "^^^

Common green glass . 2*5279 1 2-5284
Common green glass . 2*5289 J

White crown-glass . 2*44981 2-4504
White crown-glass . 2-4510 J

30 ON THE MECHANICAL PEOPERTIES OP GLASS,

TBNACITT OF GLASS.

A few espeiiments were made upon the tenacity of
glass, by tearing specimenB aaunder by a direct tensile
strEun. These results, however, owing to the following
^B- *■ circumstances, are not eo satisfactory as

could be wished. In breaking glass by
the method adopted for other materials,
viz. by suspending weights to it, there
is danger that its great rigidity and
brittlenesB may occasion ita fracture be-
fore the entire cohesive force has been
balanced by the strain applied, from the
vibration of laying on the weighte. In
the experiments upon globes, however,
in which a uniform water pressure was
employed, the tenacity of the glass was
ascertained with more accuracy, and any
failure in the present experiments is,
therefore, the less to be regretted. The
glass to be broken by a tensile strain was
obtained of the form shown in fig. 4,
drawn smaller at the middle to secure
fracture at that part. These specimens were fixed in a
pair of wrought-iron shackles, and rested by their shoulders
upon a thick india-rubber washer placed on the turned
faces of the shackles. In this state they were suspended
to a firm support, and a scale-pan attached to the lower
shackle. Weights were then added, with the greatest
care, till the specimen fractured. In this manner the
following results were obtained : —

and resistance op glass vessels to collapse. 51

Experiment 1.
Annealed Flint-glass.

Least diameter , , 0*57 in.

Least area • • • 0-255 sq. in.
Breaking weighty 583 lbs. = 2286 lbs. per square inch.

The fracture took place at a^ fig. 4, and presented a
regular smooth convex surface. No notch had been cut
in this specimen.

Experiment 2.

Annealed Flint-glass.

Least diameter . • 0*50 in.
Least area • . • 0*196 sq. in.
Breaking weight, 499 lbs. = 2540 lbs. per square inch.

Broke in the notch at b^ fig. 4, which in this case was
cut by the grindstone. It is possible that the exterior
coat of glass may be stronger than its core, in which case
the above specimen was weakened. In the next experi-
ments the specimens were drawn thinner by heat.

Experiment 3«

Common Green Glass.

Least diameter • • 0*53 in.
Least area « • . 0*220 sq. in.
Breaking weight, 639 lbs. = 2896 lbs. per square inch.

Experiment 4.

White Crown-glass,

Least diameter • « 0*54 in.

Least area , . , . 0*229 sq. in.
Breaking weight, 583 lbs. = 2545 lbs. per square inch.

Broke at shoulder a, fig. 1.

8 2

52 ON THE MECHANICAL PROPERTIES OF GLASS,

The following Table exhibits at one view the results of
these experiments, which, notwithstanding the objections
to the method by which they were obtained, appear to be
consistent with each other.

Table I. — Tensile Strength of Glass Bars.

Description of Crlass.

Area of Speci-
men, in inches.

Breaking
Weight, in lb6.

Tenacity per square inch.

in lbs.

in tons.

Flint-glass. . .. .]

Green glass . . .
Crown-glass . « .

0-255
0196
0-220
0-229

583
499
639
583

2286
2540
2896
2546

102
113
1-29
114

It may be observed here, in anticipation, that the ten-
sile strength is much smaller in the case of glass fractured
by a direct strain in the form of bars, than when burst by
internal pressure in the form of thin globes. This differ-
ence is no doubt mainly due to the fact that thin plates
of this material generally possess a higher tenacity than
stout bars, which, under the most favourable circumstances,
may be but imperfectly annealed. There is also a consi-
derable discrepancy between the strength of green and
crown-glass when in the form of bars and when in the
form of globes. In the case of the bars, the results are
as 1*0 to 1*13 in favour of green glass, whilst in the case
of the globes, the results are as 1*0 to 1*2 in favour of
the crown-glass. These discrepancies may, however, be
accounted for from the different condition of the material
in relation to annealing in the two cases, or from an im-
perfect bedding of the specimen, causing a distortion of
the strain out of the direction of the axis of the specimen,
or from accidental vibration in laying on the weights.

AND BE8I8TANCE OP GLASS VESSELS XO COLLAPSE. 53

SECTION II.
BG81STANCE OF GLASS TO CBU8HINQ.

The next series of experiments was instituted with a
Tiew of determining the powers of resistance of glass to a
direct crusting force. The speeioieas subjected to experi-
ment were small cylinders (fig. 5) varjing in length from

Fig. 5.

1 to 2 inches, and about three-quarters of an inch in dia^
meter. They were placed for the purpose of crushing
within the box a (fig. 6), thin packioga of soft lead being
interposed between the glass and the parallel crushing
surfaces of tlie box and its solid steel piston b ; in this
way a firm and uniform bearing surface was secured, and
the crushiag force was applied perpendicularly in the
direction of the axis of the specimen. Fig. 6 exhibits the
general arrangement of the crushing apparatus, consisting
of a lerer A, 6 feet long, supported on a strong cast-iron
base B, B. The crushing force obtained by placing
weights in the scale-pan hung at the extremity of the
lever is transmitted through the piston b, to the specimen
to be crushed, c.

54 ON THE MECHANICAL PROPERTIES OF GLASS,
Kg. 6.

j!ral» , in* •

AND RESISTANCE OF GLASS VESSELS TO C0LLAP8E» 65

1*0 inch.

"Weights
added,
in lbs.

224

112

Flint-glass Cylinders.
Experiment 1.

Diameter • . • 0*85 inch.
Area • * • 0*5674 square inch.

Height • • • 1*0 inch.
Placed between india-rubber packings.

This specimen having been slightly fractured at an
early stage in the experiment^ it was taken out and the
fractured side ground flat preparatory to another triaL

Experiment 2.

The same specimen as in Experiment 1.

Fig. r.

Diameter . . . 0'85 inch.

Height of segment (ab) • 0*73 inch.

Area .... 0*555 inch. I I J

Height of specimen • ^ '^ ^^'^^ ^ — * — ^

Weights Total

added, weight,

in lbs. in Ihg.

1321 1321

2080 3401

896 4297

896 5193

896 6089

896 6985

896 7881

448 8329

448 8777

448 9225 Fractured

224 9449

224 9673

224 9897

224 10121

224 10345

Fractured with 9,225 lbs. =;= 16,621 lbs.

Crushed with 13,033 lbs. = 23,483 lbs*

*rotai
weight,
in lbs.

10569
10793
11017
11^41
11465
11689
11913
12137
12361
12585
12697
12809
12921
13033 Crushed

per square inch,
per square inch*

56 ON THE MECHANICAL PROPERTIES OF GLASS^

It will not be necessary again to repeat in detail the
steps by which the weights were augmented, as these
were similar in every case. In the succeeding experi-
ments the weights at which the specimens fractured and
crushed are alone given.

Experiment 3.

Diameter . . . 0-69 inch.

Area • . . 0*37 39 square inch.

Height . • .1-0 inch.

Fractured with 11,465 lbs. = 30,661 lbs. per square inch.
Crushed with 13,033 lbs. =34,854 lbs. per square inch.

Experiment 4*.

Diameter . . • 0*70 inch.

Area • . • 0*3848 square inch.

Height . . . 1*55 inch.

Crushed suddenly with 5193 lbs. = 13,494 lbs. per .

square inch.

Experiment 5.

Diameter . . . 0*83 inch.

Area. . • • 0*541 square inch.

Height . . .1*6 inch.

Crushed suddenly with 11,241 lbs. = 20,775 lbs. per

square inch.

Experiment 6.

Diameter . . • 0*68 inch.

Area . • . 0*3631 square inch.

Height . • • 2 05 inches.

Crushed with. 11,913 lbs.= 32,803 lbs. per square inch.

* This experiment is sq eyidentlj anomaloin, that there can be little
donbt that, the bedding surfaces were not paralleU hence this result is
omitted in the following averages.

AND BESISTANCE OF GLASS VESSELS TO COLLAPSE. 67

Green Glass Cylinders.

Experiment 7.

Diameter . . .0*77 inch.

Area . . , 0*466 square inch.

Height . . . I'Oinch.

Fractured with 6933 lbs. = 14,888 lbs. per square inch.
Crushed with 10^516 lbs. = 22,583 lbs. per square inch.

Experiment 8.

Diameter • . . 0*76 inch.

Area < • • 0*454 square inch.

Height • • p 1*5 inch.

Fractured with 8126 lbs. = 17,883 lbs. per square inch.
Crushed with 15,891 lbs, =35,029 lbs. per square in6L

Experiment 9,

Diameter . . .0*79 inch.

Area • • • 0*4901 square Inch.

Height . • • 2*0 inches.

Sustained a weight of 18,634 lbs. = 38,01 5 lbs. per square
inch, without being crushed. At this point the deflection
of the lever was so great, that it was considered dan-
gerous to proceed. On removing the specimen to a
heavier lever, it crushed with a force of 12,000 lbs. The
larger weight, however, had been fairly supported.

Croion-glass Cylinders.

The two cylinders of crown-glass were slightly rounded
towards the edge of the bearing surfaces, which reduced
the area directly subjected to the crushing force. It Is
therefore probably inost accurate to take the less area in
reducing the results.

58 ON THE MECHANICAL PROPERTIES OP GLASS,

Diameter

Area
Height

Experiment 10.

{0*72 inch at middle.
0-68 inch at ends.

. 0*363 square inch.

* 1*5 inch.

Crushed suddenly with 14,100 lbs. = 38,825 lbs. per

square inch.

Experiment li.

Tx. . r 0*80 inch at middle.

Diameter . • . | ^.^g j^^^ ^^ ^^^^^

Area » » % 0*454 square inch.

Height . . • 1*0 inch.

Crushed suddenly with 10,516 lbs. = 23,181 lbs. per

square inch*

Arranging the above results together, we obtain the
following general Table of the results of the experi-
ments : —

Table II. — Summary of Results of Experiments on the
Resistance of Annealed Glass Cylinders to Crushing,

Deseriptioa of OImb.

Height of

Cylinder in

inches.

Are* of
Cylinder,
in inches.

WeiKht

Fntcture,
in lbs.

Cmahing
Weigtin

Weight per
sq. in. to

caiueFrac-

ture,

in lbs.

Weight
peraq. ia.
to Crush,
inlbi.

Flint-glass . . • .^

1*00
100
1*60
2*05

0-555
0*374
0-541
0*363

9,225
11,465

• •

13,033
13,033
11,241
11,913

16.621
80»661

• •

23,483
34,854
20,775
32,803

Green glass • • •)

1*00
1-50
2-00

0-466
0*454
0*490

6,933
8,126

10,516
15.891
18,634

14.888
17,883

• •

22,583
35,029
38,016

Crowo>glass • * •!

1*0
1*6

0*454
0*363

• 4

• •

10,516
14.100

• «

• •

23,181
38,825

• -Taking the means of the above values, and reducing
the weights to tons, we have i-^

AND KESISTANCE OF GLASS VESSELS TO COLLAPSE* 59

Table III. — Mean Compressive Resistance of Glass.

Description of Glass.

Height of
Cylinder
in inches.

Crushing Weight per
square inch,

Mean crushing Weight per
square inch,

in lbs.

in tons.

in lbs.

in tons.

Flint-glass . •<

1-0
1-6
20

29,168
20,775
32,803

13-021

9-274

14*644

U7,582

12-313

Green glass . . -

10
1-5
20

22,583
35,029
38,015

10 081
15-628
16-971

31,876

14-227

Crown-glass . . j

1-0
1-5

23,181
38,825

10-348
17-332

1 31 ,003

13*840

The mean resistance of glass to a crushing force is,
therefore, from the above experiments, equivalent to
13*460 tons per square inch. Assuming the above num-
bers to represent the comparative values of each kind of
glass, and taking flint-glass as the standard, we have their
respective strengths as follow : — ^

Green glass . .

. 1152

Crovrn-glass «

•. 1124

Flint-glass . .

. 1000

The specimens were crushed almost to powder from the
violence of the concussion, when they gave way ; it how-
ever appeared that the fractures occurred in vertical
planes, splitting up the specimen in all directions. This
characteristic mode of disintegration has been noticed
before, especially with vitrified brick and indurated lime-
stone. The experiments following on cubes of glass, which
were exposed to view during the crushing process, illus-
trated this subject further ; cracks were noticed to form
some time before the. specimen finally gave way ; then

60 ON THE MECHANICAL PBOPERTIES OP GLASS,

these rapidly increased in number, splitting the glaas into
innumerable irregular prisms of the same height as the
cube ; finally these bent or broke, and the pressure, no
longer bedded on a firm surface, destroyed the specimen.
Fig. g. The annexed ideal sketch (fig. 8) may give
ri some notion of the fractures of a cube, sup-
posing all the particles were restored to their
position after crushing.

The specimens employed in the following
experiments were cut from the square heads
of the pieces of glass employed in the experiments on
tensile strun (fig. 4). These pieces were approximately
cubical, and their size prevented their insertion in the
box a (fig. 6) ; they were, therefore, crushed between par-
rallel steel discs, exposed to view. The crushing was
more gradual, and was not effected so completely in these
experiments as in those on small cylinders, the fragments
being in every case larger after the conclusion of the ex-
periment: it must further be recollected, in comparing
these with the preceding experiments, that the cylinders
were cut aS, of the required length, from rods of glass
drawn out when molten to the diameter desired, so as to
retain the first-cooled exterior skin of glass, which is prob-
ably of greater tenacity than the interior; on the other
hand, the cubes were cut from the centre of larger lumps
of glass, and were possibly in a state of imperfect an-
nealing.

Flint-glass Cubes.
Experiment 12.

Area = 0-96 x 0-97 inch=0-9312 square inch.
Heigbt= 1-15 inch.
Crushed suddenly with 13,257 lbs. = 14,235 lbs. per
square inch.

and resistance op glass vessels to collapse. 61

Experiment 13.

Area = 0-99 x 0-98 inch =s 0-9 702 square inch.
Height = 1-16 inch.
Crushed with 12,809 lbs. = 13,202 lbs. per square inch.

Experiment 14.

Area =0-98 x 1-02 inch = 0-9996 square inch.
Height =1*10 inch.
Crushed with 13,257 lbs. = 13,262 lbs. per square inch.

Experiment 15.

Area = 0*98 inch x 0*98 in. = 0*9604 square inch.

Height= 1-10 inch.
Fractured with 6537 lbs.= 6806 lbs. per square inch.
Crushed with 11,353 lb8.= 11,820 lbs. per square inch.

Green Glass Cubes.
Experiment 16.

Area = TO x 0*98 inch = 0*98 square inch.
Height =1*0 inch.
Crushed with 20,059 lbs. = 20,468 lbs. per square inch.

Experiment 17.

Area =0*99 x 1*2 inch =1*188 square inch.
Height = 1*0 inch.
Crushed with 23,535 lbs. = 19,945 lbs. per square inch.

Crown-glass Cube.

Experiment 18.

Area =0-82 x 0*92 inch =0*7534 square inch.
Height =0*9 inch.
Crushed with 16,475 lbs. = 21,867 lbs. per square inch.

This crushed suddenly after bearing the weight some
time, and was reduced almost to powder.

62 ON THE MECHANICAL PROPERTIES OF GLASS,

Table IV. — Summary of the Results of Experiments on
the Resistance of Cut Glass Cubes to Compression.

Description of Glass.

Area of Spe-
cimen, in
square inch.

Crushing
Weight in lbs.

Resistance to Crushing per
square inch.

in lbs.

in tons.

Flint-glass . . .-

0-9312
0-9702
0-9996
0-9604

13,257
12,809
13,257
11,353

14,235
13,202
13,262
11,820

6-355
5-894
5-921
5-276

Green glass , . .•!

0-9800
1-1880

20,059
23,535

20,468
19,945

9-116
8-904

Crown-glass . . .

0-7534

16,475

21,867

9-762

Hence the mean resistance to crushing of cubes of glass

is equivalent to a weight of —

lbs.

For flint-glass . • 13,130

For green glass , . 20,206

For crown-glass . . 21,867

Mean . . 18,401

Comparing these with the preceding results on glass
cylinders, we have the mean resistance of the former
experiments to the mean resistance of the above as
30,153 : 18,401, or as 1-6 : 1.

General Observations relative to the Results of the Expert'
ments on the Resistance of Glass Cylinders and Cubes to
Crushing,

With iron and some other materials, when a short
column undergoes a pressure in the direction of its length,
rupture takes place in a plane having a determinate angle
to the axis of the column, this plane being the section of
least resistance. Neglecting the friction of the surfaces.

AND BESISTANOE OF GLASS VESSELS TO COLLAPSE. 63

Coulomb found this angle to be 45°, and allowing on an
average 10** for the limiting angle of friction, the angle of
the plane of rupture may be taken at 55!^, To fulfil this
condition, the length of the column to be crushed should
be at least three times its radius : when the length greatly
exceeds this limit, the rupture will be effected by the ten-
dency of the column to bend; and when the length is
within this limit, the force requisite to produce rupture
will be increased in consequence of the irregular form of
the line of fracture. These theoretical deductions have
been confirmed by experiments made upon columns of
iron, wood, bone, stone, and other materials. The
results of the experiments here recorded, however,
show that when the length of the cylinder does not
greatly differ from three times its radius, the resistance
to a crushing force is pretty nearly a constant, viz. on au
average 12*313 tons per square inch in the case of flint*
glass, 14*227 tons in the case of green glass, and 13*84
tons in the case of crown-glass. But, according to Cou-
lomb's law, the cubes of flint-glass (their lengths being
considerably less than three times their semi-diameters)
should have presented higher powers of resistance than
the cylinders; this discrepancy is probably owing to the
injury which the glass had sustained in the process of
cutting, and to the imperfect annealing of glass when
cast in the form of cubes and cylinders.

SECTION ni.

BESISTANCE OS" GLASS GLOBES AND CYLIKDERS TO

INTERNAL PRESSURE.

In the following experiments it has been sought not
only to determine the law of resistance to internal pres-
sure, which is already well known from theoretical con-

64 ON THE MECHANICAL PEOPERTIES OF GLASS,

siderations, but to ascertain the direct tensile strength of
the glass (of which the bursting pressure is a function) by
a method free from many of the objections to that described
in Section I. The bursting pressure of cylindrical and
spherical vessels is well known to be in the ratio of the te-
nacity of the material, other things being the same, and
the determination of the tensile strength upon this principle
presents in the case of glass peculiar advantages. As glass
can be obtained in tolerably perfect spheres, and as the
fracture of these may be effected by a uniform water pres-
sure, increasing slowly and regularly without vibration,
there is a better chance of ascertaining the ultimate resist-
ance of the material, from the absence of those shocks and
irregularities which are inseparable from any process de-
pending upon the piling up of weights, however carefully
conducted.

In making these experiments, a number of glass globes
were procured of varying size and thickness. The stems

were then flanched out by the blowpipe
(fig. 9), and the diameter having been
carefully measured, they were ready for
experiment. To effect their rupture,
each globe, k (fig. 10), was attached by
means of a stufling-box (a) to the cover
of a strong wrought-iron boiler B, and
was enclosed by the iron cylindrical vessel
d, to prevent the dispersion of the frag-
ments when rupture took place. In the
stuffing-box the flanch of the stein of the globe was bedded
upon vulcanised india-rubber in such a manner as to secure
a water-tight attachment without impeding the access of
the water to the interior of the globe. The boiler was
connected with a hydraulic pump by means of the pipe ^,
and an accurate gauge of the Schaeffer construction was
fixed to the boiler to register the pressure. With this ar-
rangement it will be seen that as the pumping was con-

AND BESISTAKCE OF GLASS VESSELS TO COLLAPSE. 65

tinued the water would rise in the globe, cooipreBsing the
air in ita interior, progreseivelf , up to the point at which
the resistance of the glass was overcome by the expansive
force of the fluid ; at that point explosion would take place,
the pressure in pounds per square inch being noted both
by the eye of the observer and by the maximum finger of
the gauge.

T,g. 10.

66 ON THE MECHANICAL PROPERTIES OF OLASS^

In glass globes generally, the upper half of the sphere
a^ by c (fig. 9) is the most spherical, and is approximately
uniform in thickness, being, however, thinnest at &, and
thickening gradually downwards towards the stem, the
lower half (a, d^ c) being considerably the strongest.
Hence it happened, in several cases (in fact in every case
in which the point could be determined with certainty from
the condition of the fragments), that the globes ruptured
first at b, the lines of fracture radiating in every direction,
passing round the globe as meridians of longitude, and split-
ting it up into thin bands, varying from -gi^^th to ^th inch
in width. In the case of some elongated ellipsoids, it ap-
peared that the fractures occurred horizontally, or perhaps
obliquely, from the condition of the fragments attached to
the stem. In most cases, however, it was not clear from
the fragments which had been the direction of the frac-
ture, although the mode of rupture was the same in every
case.

To ascertain the thickness, several specimens were se-
lected from the thinnest fragments, and each being mea-
sured separately by a micrometer screw of fifty threads to
the inch and reading on a graduated head to ^^^jth of an
inch, the minimum thickness was assumed as that of the
part which ruptured, and has been employed in reducing
the results.

It must also be observed that the globes were usually
slightly elliptical, in some cases seriously so ; the vertical
diameter, b d (using the same form of expression as before)
being generally less than the horizontal, a c. In the fol-
lowing Tables the two diameters are given in each case : —

AND RESISTANCE OF GLASS VESSELS TO COLLAPSE. 67

Flint-glass^

El^PBRIMENT 1.

Globe a. Diameters 4*0 and 3*98 inches.

In parts of an inch.
^^0*0230
0*0256
0*0284
0*0244
0*0302
0*0250
0*0240

Thicknesses measured <<

► Minimum = 0*024 inch.

Bursting pressure =84 lbs. per square inch.

Experiment 2. W tvv. '

Globe b. Diameters 4*0 and 3*98 inches.

tn parts of an inch.
0-034
0*032
0*031
Thicknesses measured •{ 0*0254 V Minimum =0*025 inch.

0*0256
0031
0*028

Bursting pressure =93 lbs. per square inch. //

Experiment 3.
Globe c. Diameter 4*0 inches.

In parts of an inch,
f0*040 ■]
0*0406
Thicknesses measured -{ 039 > Minimum =0*038 inch.

I 0*039 I
1^0*038 J

Bursting pressure = 150 lbs,, per square inch.

31^7 /I'^c^

68 ON THE MECHAKICAL PROPERTIES OF CLASS,

Experiment 4.
Globe d. Diameters 4*5 and 4*55 inches.

In parts of an inch.
0-0620
0-0694
0-0584
0-0626
0-0564
0-0614
0-0604
0-0580

Burst with 280 lbs. per square inch.

Thicknesses measured i

>• Minimum s=0-056 inch.

Experiment 5.
Ghhe e. Diameters 5'1 and 5*12 inches.

In parts of an inch.
^0-0580'
0-059
0-0586
0-0634 i
0-0620
0-059

Burst with 184 lbs. per square inch.

Thicknesses measured^

> Minimum =0*058 inch.

Experiment 6.
Globe/. Diameter 6*0 inches.

In parts of an inch.
0-060 "^
0-066

Thicknesses measured -l Q.Q^g V Minimum = 0-059 inch.

0-0*592
0-0592

Burst with 152 lbs. per square inch.

AND RESISTANCE OP GLASS TE8SELS TO COLLAPSE. 69

Thicknesses measured <

Minimum
^ = 0-079
inch*

« — ^ — .>

BXPERIMEKT 7.

Cylinder g. Diameter 4*05 inches. Length 7 O inches.

In parts of an inch.

0-081
0-090
0-086
0-086
0-079
0-086

Burst with 282 lbs. per square inch.

Green Cflast,

Experiment 8.

Globe A. Diameters 4*95 and 5*0 inches.

In parts of an inch,
0-029
0-024
0-026

0-025 h Minimum = 0-022 inch.

Thicknesses measured ^

0-023
0-024
0-0225
Bursting pressure ^s 90 lbs. per square inch^

Experiment 9.
Globe L Diameters 4*95 and 5-0 inches.

^In parts of an inch.

0-024

0-023

0-022

Thicknesses measured <

0-023 \ Minimum = 0-020 inch.

0-022
0-020
0-020

Burst with 85 lbs. per square inch.

70 OK THiJ MECflAKlCAL PROPERTIES OF GLASS^

Experiment 10.
Glole m. Diameters 4*0 and 4*05 inches.

In parts of an inch.
^0-020 ^

0-0205
1 0-0202

0-021

0*020 ^ Minimum = 0-01 8 inch.

Thicknesses measured •<

0-023
0-0205
0-0215
0-020

Bursting pressure =84 lbs. per square inch.

Experiment 11.
Globe n. Diameters 4*0 and 4-03 inches.

In parts of an inch.
'0-016
0-019
0018
Thicknesses measured-^ 0-017 VMinimum=0-016 inch.

0-019
0016
0-016

Bursting pressure =82 lbs. per square inch.

Crown-glass.

Experiment 12.

Globe p. Diameters 4-2 and 4-35 inches.

In parts of an inch.
0-0252"^
0-0270
0-0272
0-030
0-0252
0-0256
Burst with 120 lbs. per square inch.

Thicknesses measured <

>• Minimum = 0-025 inch.

AND RESISTANCE OF GLASS VESSELS TO COLLAPSE. 71

EXPEBIMENT 13.

Globe q. Diameters 4*05 and 4*20 inches.

In parts of an inch,
f 0028 ■
0*0236
0-0256
0*0236 f
0*0212
OO2I0J

Bursting pressure =126 lbs. per square inch.

Thicknesses measured ^

>^ Minimum =0*021 inch.

EXPEBIMENT 14.

Globe r. Diameters 5*9 and 5*8 inches.

In parts of an inch.
0-0334'^
0*020

Thicknesses measured ^;:2?f

> Mmimum = 0*01 6 inch.

0*0172
0*016

Burst with 691b& per square inch.

Experiment 15.

^, , rk* X f horizontal =6*0 inches.

Globe 8. Diameters { . . , /? « • l

l^ vertical = 6*3 inches.

In parts of an inch.
0*024
0*020

0*0204 ^^^^^1"^^°^= 0*020 inch.

0*0270
0*0262

Thicknesses measured

Bursting pressure =86 lbs. per square inch.

72 ON THE MECHAKICAL PB0PEBTIE8 OF GLASS,

Experiment 16.
Ellipsoid t Diameters 4*1 and 7*0 inches.

lo parts of an inch.

0-0180"^

0-0208

rni . 1 0-0220

^ Ihicknesses .'Q.QjgQ }. Minimum 0-016 inch,
measured ^ ^.^^g^ r

0-0170
0-0220

Bursting pressure = 80 lbs. per squjEire inch.

Experiment 17.
Ellipsoid V. Diameters 4-0 and 7-0 inches.

In parts of an inch.

rO-0206

0-0208

f 0-0224

0-0206 ^^J^5"^"^=^*^19 iJ^ch,

0-022

0-021

10-0254

Bursting pressure=109lb8. per square inch.

Thicknesses measured ^

Summing up the preceding results, they are arranged
in the following Table : —

AND BESIBTANCE OF GLASS VESSELS TO COLLAPSE. 73

Summary of Results.

Table V. -■■ — Resistance of Glass Globes to internal

Pressure.

Number of
Experiment.

IIL

IV.

VIIL

IX.

XIL
XIIL
XIV.

XV.

Description of Glass.

Flint-glass

^ Green glass . .<

Crown-glass. .

Diameter
in inches.

4-0
4-0

4*5
51

x3'98

x3*98

X4-55

x5*12

4-95 X 5*0
4-95 X 60
4-0 x4-05
4*0 x4'03

4-2 X4-35
405 X 4*2
5-9 x5-8
©•O X 6*3

Thlekn<As in

parts of an
inclt.

0-024
0-025
0-038
0-056
0-058
0059

0-022
020
018
0-016

0-025
0021
0-016
0-020

Bursting
Pressure in
pounds, per
square inch.

93
150
280 -
184
152

90
85
84
82

iTvuc*^

120

126
69
86

//,vv-.

3 Hi
STTTT
TTTT

s'i ;■»-

Table VL — Resistance of Glass Cylinders and

to internal Pressure.

Ellipsoids

^ ■

Number of
Experiment.

Deseription of
QAmm.

Form of Vessel.

Diameter
in inches.

Thickness, in
parts of an

tBuratine

PreMure,ln

pounds per

square in.

VII.

XVI.

XVII.

Flint-glass ....
Crown-glass . . .
Crown-glasa . . .

Cylinder .
Bllipeoid . .
Ellipsoid . .

4-05x7-0
4-1 x7'0
4*1 X7-0

0-079
0-016
0019

282

109

74 ON THE MECHANICAL PROPEETIES OF GLASS,

SECTION IV.

ON THE RESISTANCE OF GLASS GLOBES AND CYLINDERS

TO AN EXTERNAL PRESSURE*

The following experiments are in continuation of^ and
supplementary to, the researches on the collapse of wrought-
iron vessels already alluded to. In this aspect they are
the most important in their bearings and the most novel
of any in the present memoir.

The method of conducting them did not differ in any
essential detail from that pursued in the researches upon
wrought-iron tubes, described in a former paper. A
number of globes of varying dimensions were procured,
and hermetically sealed by means of the blowpipe. In
this state they were fixed in the interior of the strong
wrought-iron boiler B (fig. 10) (capable of sustaining a
pressure of about 2500 lbs. per square inch), in the posi-
tion shown at A. The boiler or vessel B communicated,
by means of the pipe a^ with a hydraulic force-pump
having a plunger of three-quarters of an inch diameter, so
that a uniform pressure of about 1000 lbs. per square inch
could easily be obtained. In order to register the pres-
sure, gauges of the Schaeffer construction* (C) were
employed, as before, affording, within small limits of error,
certain and accurate indications of the increase of pressure
obtained by the pump. The collapse of the glass vessel
was made known by a loud report, and by the instant
recession of the moveable finger of the gauge i ; the
maximum pressure obtained was marked by a second
finger A, and also, to prevent error from any accidental
cause, by the eye of the observer.

* In pressure-gauges of fhe Schaeffer construction a corrugated steel
plate measures the force, bj expanding under pressure. The indications
are communicated bj a rack and pinion to the hand of the gauge which
moves over a face plate graduated bj trial. In principle this gauge docs
not materiallj differ from the aneroid barometer.

AND RESISTANCE OF GLASS TESSEL8 TO COLLAPSE. 75

During the collapse the globes were reduced to the
smallest fragments ; in some cases a great part almost to
powder, by tlie -violence of the concueaion. Hence in

these experiments no indication could be found of the
mode in which the globes had given way, nor of the
direction of the primary lines of fracture.

76 ON THE MECHANICAL PROPERTIES OB* GLASS,

After the globe had been ruptured, the fragments were
carefully collected, and a selection having been made of
the thinnest, they were measured, as before, by means of
a micrometer-screw. The minimum thickness thus deter-
mined has been assumed for the thickness of the point of
rupture in the calculations.

Flint-glass*

Experiment 1.

Globe A, Diameters 5*05 and 4*76 inches.

In parts of an inch,

ro-0170"|
0-0192
0-0190
0'0218
00220
0-0146
0-0178
0-0164

Collapsing pressure =292 lbs. per square inch.

Thicknesses measured^

>> Minimum = 0*014 inch.

Experiment 2<
Glohe S. Diameters 508 and 4*7 inches.

In parts of an inch.

^0-0210

0-0200

0-0180

0-0200

0-0194

0-0188

0-0192
I 0-0196

Thicknesses measured ^

» Minimum = *0 1 8 inch.

Collapsing pressure =4 10 lbs. per square inclu

AND EE8ISTANCE Or GLASS VESSELS TO COLLAPSE. 77

EXPERIMEKT 3.

Globe C. Diameters 4*95 and 4*72 inches.

In partfs of an inch.

0-0214
0-0246
0-0208
0-0220
0-0266
0-0222
0-0226

Thicknesses measured^

>• Minimum = 022 inch.

Collapsing pressure =470 lbs. per square inch.'

Experiment 4.

Globe D. Diameter 5*^ inches.

Minimum thickness = 0*020 inch.
Collapsing pressure = 475 lbs. per square inch.

Experiment 5.
Globe JE. Diameters 8*22 and 7*45 inches.

In parts of an inch.

r00152"^
0*0118
0122
0-0100
0-0106
0-0128
0-0108
0-0108
00110
0*0102

Collapsing pressure = 35 lbs. per square inch..

Thicknesses measured -<

>- Minimum =0*0 10 inch.

78 ON THE MECHANICAL PROPERTIES OF GLASS,

Thicknesses measured -<

> Minimum = '0 1 2 inch.

Experiment 6.
Globe F, Diameters 8*2 and 7*2 inches.

In parts of an inch.
rO-0124"
0-0138
0-0126

O'Oiie

0-0120
00120

Collapsing pressure =42 lbs. per square inch.

Experiment 7.
Globe G. Diameters 8*2 and 7*4 inches.

In parts of an inch.
0-0160
0144
00166
00148
0-0144
0-0158
0-0164
0-0150

Collapsing pressure = 60 lbs. per square inch.

Experiment 8.

Globe H. Diameters 4 and 3-98 inches.
Minimum thickness =0-024 inch.

This globe sustained unbroken a pressure of 900 lbs.
per square inch.

Experiment 9,

Globe L Diameter 4-0 inches.

Minimum thickness =0*025 inch.

This globe sustained unbroken a pressure of 900 lbs.
per square inch.

Thicknesses measured^

>>Minimum= 0*015 inch.

AND RESISTANCE OF GLASS VESSELS TO COLLAPSE. 79

Experiment 10.

Globe K. Diameter 6*0 inches.

Minimum thickness =0*059 inch.

This globe remained unbroken with a pressure of
1000 lbs. per square inch.

Experiment 11.

Cylinder L. Diameter 3 '09 inches.

Length 14 inches.

Thicknesses measured <

In parts of an inch.

^0-0243
0-0241
0-0235
0*0238
0-0241
0-0352^
Collapsing pressure =85 lbs. per square inch.

Fig. 14.

Minimum
== 0024 inch.

Y-

Experiment 12.

Cylinder M. Diameter 3-08 inches.

Length 14 inches.

In parts of an inch.
^0-0320

Fig. 15.

Minimum
=0-032 inch.

0-0324

Thicknesses measured \ q-qs 16

0-0326
^0-0322^
Collapsing pressure =103 lbs. per square inch

80 ON THE MECHANICAL PROPERTIES OF GLASS,

Fig. 16.

Fig. 17.

Experiment 13.

Cylinder N. Diameter 3*25 inches.

Length 14 inches.

In parts of an inch.
^0-0452^
0-0436
^, • , 00472

Ihicknesses . ^.^^22 ^Minimum = 0-042 inch,
measured ^Q.(j42g^

0-0436
0-0452
Collapsing pressure's 175 lbs. per square inch.

Experiment 14.

Cylinder O. Diameter 4-05 inches.

Length 7*0 inches.
In parts of an inch.

»t* Thicknesses
measured

1-*L.

>- Minimum s= 0-034 inch.

0-0454^
0-0384
0-0368
^ 0-0344
0-0348
0-0392
0-0348

Collapsing pressure === 202 lbs. per square inch.

Experiment 15.
Cylinder P. Diameter 4-05 inches.

Length 7 inches.

Fig. 18.

Thicknesses
measured

In parts of an inch.

rO-0502^
0-0464
0460
0-0464
0-0510
0-0498

00558

«^

Collapsing pressure =380 lbs. per square inch.

> Minimum =0*046 inch.

AND RESISTANCE OF GLASS VESSELS TO COLLAPSE. 81

Experiment 16.

Cylinder Q. Diameter 4*06 inches.

Length 13*8 inches.

In parts of an inch.

0-0448

0*050

a-t)474

Thicknesses measured -{ r^.^A'ja

Fig. 19.

I Minimum

^ =0-043 inch.

0-0470

0-053

0-0434

Collapsing pressure =180 lbs. per square

inch. V

Experiment 17.

Cylinder R. Diameter 4*02 inches.

Length 13-8 inches.

In parts of an inch. Fig. 20.

^0-0678

Thicknesses measured^

0-0664
00728
00718
0-0660
0-0644
0-0706
0-0682

Minimum
=0-064 inch.

Collapsing pressures 297 lbs. per square inch.

82 ON THE MECHANICAL PROPERTIES OF GLASS^

Fig. 21.

Experiment 18,

Cylinder 5. Diameter 3 '98 inches.

Length 14*'0 inches.

In parts of an inch.

^0-0792 "I
0-0774
0-0762
0-0812
0-0828
00848
0-0836
0-0778
0-0766J

Thicknesses
measured

^Minimum =0-076 inch.

Collapsing pressure =382 lbs. per square inch.

Experiment 19.

Cylinder T. Diameter 4*05 inches.

Length 7'0 inches.

In parts of an inch.

^0079^
0-081
0-090
0-086

V Thicknesses

measured

>• Minimum =0-079 inch.

0-086
0-079
086

This cylinder remained unhroken after sustaining a pres"
sure of 500 lbs. per square inch.

AND BESI8TANCE OP GLASS VESSELS TO COLLAPSE. 83

Thicknesses measured ^

Experiment 20*.

Cylinder V* Diameter 4*2 inches.

Length 22 inches.

In parts of an inch,

^0-063
0-056
0-057
0-055
0-057
0-055
0-056

>- Minimum =0-055 inch.

Collapsed with 120 lbs. per square inch.

Experiment 21*.

Cylinder W. Diameter 4-1 inches.

Length 21*5 inches.

In parts of an inch.

0-0535

0-051

0-055

0-052

0053

060

0057

00525

0-055

Collapsed with 129 lbs, pressure per square inch.

Thicknesses measured <

>► Minimum =0051 inch.

* The experiments marked with an asterisk were not originally included
in the calculations ; hut the results are strictly in conformity with those
previously reduced.

84 ON THE MECHANICAL PROPERTIES OF 6LASS5

Experiment 22*.

Cylinder X. Diameter 4*2 and 4*1 inches.

Length 22 inches.

In parts of an inch.

'0-0455

0-047

0-049

0-047

Thicknesses measured^ ^iJJJ j^Minunum= 0-0455

0-047
0-049
0-047
0-054
0-046

Collapsing pressure = 125 lbs. per square inch.

Green Glass.

Experiment 23.

Globe Z. Diameters 5-0 and 5*02 inches.

In parts of an inch.

^0-015
0-013
0-0125
0-019
0-016
0-018
0-021
0-0126
0-013

Collapsed with 212 lbs. per square inch.

Thicknesses measured <

^Minimum =0-0 125
inch.

AND BESISTAKCE OF GLASS VESSELS TO COLLAPSE. 85

Table VII. — Summary of the Results of JExperiments
on the Resistance of Glass Globes to an External
Pressure,

Number of
Experiment.

Description of Glass.

Diameters,
in inches.

Minimum
Thickness,
iu inches.

Collapsing

Pressure per

square inch,

in lbs.

111.

IV.

\iL

VIIL

IX.

Flint-glass; . .-

J N.

■ 5*05 and 4*76
5*08 and 4*7
4*95 and 4*72

56
8*22 and 7*45
8-2 and 7*2
8-2 and 7*4
4*0 and 3*98

6*0

0*014*

0018

0*022

020

0*010

0*012

0015

0*024

0*025

0059

292
410
470
475

35 :

42
60
(900)»
(900)»
(1000)*

xxni.

Green glass • .

50 and 5*02

00125

212

Table VIIL — Summary of Results of Experiments on the
Resistance of Glass Cylinders to an External Force.

Number of
Experiment.

Description of Glass.

Diameters,
in inches.

Length, in
inches.

Minimum
Thickness,
in inches.

Collapsing

Pressure,

per square

inch, in lbs.

"\ f

309

14*0

0024

XIL

3*08

14*0

0032

103

XIIL

3*25

14*0

0*042

175

XIV.

4*05

7*0

0*034

202

XV.

4*05

7-0

0*046

380

XVL
XVIL

'Flint-glass .

4 06
4*02

13*8
13-8

0*043
0*064

180
297

XVIIL

3*98

14*0

0*076

382

XIX.

4*05

7*0

0*079

(500)t

XX.

4*20

22*0

0*055

120

XX T.

4*10

21*5

0*051

129

XX IT.

-' I

' 4*15

22*0

0*046

125

* These globes remained unbroken*

Q 3

f Bemained unbroken.

86 ON THE MECHANICAL PROPERTIES OP GLASS^

SECTION V.

REDUCTION OP THE PRECEDING RESULTS.

L Generalisation of the Results of Experiments on the
. Resistance of Glass Globes and Cylinders to External
Pressure.

Let us assume —

P = the external pressure in pounds per square inch to
produce rupture.

D = the diameter of the globe or tube, as the case may
be, in inches.

k = the thickness of the glass in inches.

p = the pressure P reduced to unity of thickness, viz.
A ='01 inch.

C, a, /3, constants to be determined from the data sup-
plied by the experiments.

Then for the globes we assume

P=]q;8> • • * ' (0
and for the cylinders

EPTZ' • • • (^)

where the exponent of the thickness is the same in both
formulse.

Hence we find for globes of the same diameter and also
for cylinders of the same length and diameter —

_l0gP,-l0crP,

log A, -log Ag

Taking the results of Experiments 1 and 2, we find
a=l'35; from 5 and 6 we find a=l*33; from II and
12 we find a=l-28; from 16 and 17 we find a= 1-26;

AND RESISTAKCE OF GLASS VESSELS TO COLLAPSE, 87

and from 15 and 16 we find a =2. Hence we get for
the mean value of a^

a=;J-{l-35 + l'33 + l'28 + l-26 + 2} = l-4.

Again^ the following formula enables us to reduce the
pressure P, of the cylinders as well as of the globes, to
unity of thickness,

logj9=logP-alog(100 A) . . (4)

Making these calculations, we obtsdn the following
Tables of results : —

Table IX. — Reduction of the Results of Experiments
on the Resistance of Glass Globes to Unity of Thickness*

Number of
Experiment.

Diameter,
in inches.

Thickness,
in inches.

P.
Collapsing Pres-
sure, in lbs. per
square nch.

P-
P reduced
to Unity of
Thickness.

L
TT.

in.

IV.

VTI.

6-05
5-08
4-95
6-60
8-22
8-20
8-20

•014
•018
•022
•020
•010
•012
•015

292

410

470

475

178

168

156

180
35

32-54
3401

Table X. — Reduction of the Results of Experiments on
the Resistance of Glass Cylinders to Unity of Thickness,

Number of
experiment

D.
Diameter,
in inches.

Length,
in inches.

k.
Thickness,
in inches.

P.
Collapsing Pres-
sure, in lbs. per
square inch.

P reduced

to Unity of

Thickness.

3^09

0024

27-36

XXL

308

032

103

20-23

XIII.

3-25

0-042

175

23-47

XIV.

4-05

0-034

202

36*41

XV.

4^05

0046

380

44-86

XVL

4-09

138

0043

180

23-36

XVIL

4-02

138

0*064

297

22-10

xvni.

3-98

0076

382

22-33

o 4

88 ON THE MECHANICAL PROPEBTTES OF GLASS,

Let Dj, pi be put for the data derived from Experiment
1 ; Dg, P2 for the data derived from Experiment 2, and so
on ; then we get from equation (1),

Q _ ^og ;>! + ^og Pi + ^og Pa - Qog P$ + ^og Ps + ^og Pi) (K\

logDj + logD. + logD^-GogJD. + logDj + logDj) ' * ^^

f^_ \0gp^-l0gpj (g)

log D7— log Di "'■■'•

ft ^ log Pa + ^Og Pa ^- ^Og P4 - QQg P^ + ^Qg Pg + ^Qg P7) (7)

log D4 + log De + log D7 - (Aog D3 + log D, + log JDJ

From equation (5) we find /8=3'43; from equation (6)
we find /8=3'25 ; and from equation (7) we find /8=3'56 ;
and the mean of these values gives

/8=i(3-43 + 3-25 + 3-56)= 3-4.
For the value of the constant C, we find

logC=|(log;?i + +log;77) +

^(logDj + + logD7) + 2a, . (8)

whence we find C = 28,3 0,000.

Substituting the values of a, /8, C thus obtained in the
general formula (1), we get

P=28,300,000x^ . • (9)

which is the general formula for calculating the strength
of flint-glass globes subjected to external pressure. In
order to facilitate calculation, this formula may be written

log P=4-6518 + 1-4 log (100 *)-3-4 log D . (10)

Calculating the value of P by this formula from the
data of Experiment 23, viz. D=5 and A = '0125, we find

log P=4-6518 + 1-4 log 1-25-3-4 log 5=:log 258,
that is P= 258 lbs. Now this would be the crushing

AND RESISTANCE OF GLASS VESSELS TO COLLAPSE. 89

pressure supposing the globe to be flint-glass; but the
crushing pressure given by the experiment is 212 lbs.;
hence it appears that the resistance of green glass 4o ex-
ternal pressure differs very little from that of flint-glass.
The following Table will show how nearly formula (9)
represents the results of the experiments on glass globes.

Table XI. — Results of Experiments on the Resistance of
Glass Globes to External Pressure,

Number of
Experiment.

by Experi-
ment.

by Formula
(9).

Proportional
Error by
Formula.

III.

IV.

VII.

VIIT.

TX.

XXIIL

5-05

5-08

4-95

6-6

8 22

8^2

8-2

4-0

6-0

502

•014
♦018
•022
•620
•010
•012
•015
•024
•025
•059
•0125

292
410
470
475
35
42
60
900*
900*
1000*
212t

292

408

580

340

44-8

61-3

1370

1450

1218

258

100

+ F0

+ J

The lengths of the cylinders of Experiments 11, 12,
and 13 are the same, and their diameters are nearly
equal to one another. The same observation applies to
the cylinders of Experiments 14 and 15, and also to
Experiments 16 and 71. In order, therefore, to reduce
the pressures p to uniformity of diameter, we may as-
sume, for such small differences, that D varies as ^,

These reductions being made, we may obtain the following
Table :—

Bemained nnbroken.

t Green glass.

90 ON THE MECHANICAL PEOPERTIES OF GLASS,

Table XII. — Reduction of the Results of Experiments on
Glass Cylinders to uniformity of Diameter y Sfc.

Number of
Experiment

D.
Diameter,
initiclies.

Length,
in incites.

P reduced to Unity
of Tiiicknesg.

pD L.

11, 12, 13,
14, 15,
16, 17,
18.

4-05
4 05
3 98

13-8
14

24-81
4063
22-67
22-33

1042
1151
1260
1240

Mean value of p L D =— ^

'^ 1173

Here the continued product of the pressure, diameter,
and length is shown to be very^early a constant quantity,
the thickness of the glass being the same, that is for
A=*01. Hence we have

•01"

(11)

Now the mean value of pDL is 1173, as shown In
Table Xll, and a=l*4, as determined by equation (3);
hence we find

0=111?.= 740,000.

.011-4

Substituting these values of the constants in equa-
tion (2), we get

P = 740,000

DL'

. (12)

which IS the general formula for calculating the strength
of glass cylinders subjected to external pressure, within
the limits indicated by the experiments, that Is, provided
their length is not less than twice their diameter, and not
greater probably than six times their diameter. This law

AND BESISTANGE OP GLASS VESSELS TO COLLAPSE. 91

of strength is precisely similar to that found for sheet-iron
tubes.

For convenience of calculation^ this formula may be
written

log P = 3-06923 + 1-4 log (100 A)-log (DL) . (13)

The following Table will show how nearly formula
(12) represents the results of the experiments on glass
cylinders : —

Table XIII. — Results of Experiments on the Resistance of
Glass Cylinders to External Pressure,

Number of

by Formula.

Proportional

Experi-
ment.

by Experi-
ment

Error by
Formula.

XI.

309

•024

+ I7J
+ 4

+ 1

XII.

3-08

•032

103

138

XllL

3-25

•042

175

192

XIV.

4-06

•034

202

227

+ A

XV.

4-05

•046

380

361

XVL

4-06

138

•043

180

161

XVIL

4*02

13-8

•064

297

284

_ 1

XVIII.

3-98

•076

382

361

"~\

XTX.

4-05

•079

500

747

Unbroken.

XX.

4-2

•065

120

138

+ J^

XXL

21-5

•051

129

130

+ J2ff

XXTL

4-2

•0455

125

107

Comparative Strength of Glass and Sheet-iron Cylinders
subjected to an External Pressure tending to produce
Collapse.

The formula of strength for sheet-iron cylinders, after
reducing L to inches, is

F=806,300xl2x^.
Now for cylinders of the same diameter, length, and

92 ON THE MECHANICAL PROPERTIES OP GLASS,

thickness, we find, by dividing equation (12) by the
above,

p p9" • • • • VA*;

When A = '043, as in most of the experiments on iron,

P 11
then— = — ; that is, in this case, the strengths of the

two cylinders will be nearly equal to one another.

II. Generalisation of the Results of the Experiments on the
Resistance of Glass Globes^ Cylinders^ and Ellipsoids to
Internal Pressure.

Let D = the diameter of the globe or cylinder, as the

case may be.
X;=the thickness of the material in inches.
a=the longitudinal sectional area of the material

in square inches ; that is, in the direction of

the line of rupture, or line of minimum

strength.
A=the longitudinal section in square inches.
P = the bursting pressure in lbs. per square inch.
T=the tenacity of the material in lbs. per square

inch.

Then we find

P=^; .... (15)

T=^; .... (16)
a

that is, is a constant for vessels of the same material.

This theoretical deduction is ftiUy confirmed by the results

of these experiments, as arranged in the following Table : —

AND BESISTAKCE OF GLASS VESSELS TO COLLAPSE. 93

Table XIV. — Resistance of Glass Globes^ Cylinders^ and
Ellipsoids to an Internal Pressure.

Nnmber
of Ex-

Dewriptionof OImi.

1;.

Yalneof
P^

Mean
Value of

P^.
a

periment.

• a

■^ f

4-0 and 3-98

*024

3500

•^

4*0 and 3*98

•025

8710

4-0

•038

150

8950

[■Flint-glaM .-

4-5 and 4S5

•a56

280

5650

M200

61 and 512

•068

184

4050

6-0

•059

152

8870

J V.

4-05 and 7*0

•079

282

4660

^ c

4-95 and 6*0

•022

4040 ^

l^ , J

4*95 and 5*0

•020

6280 t ^«««

10.

> Qreen glass *<

40 and 405

•018

4690 f««>

11.

) L

4-0 and 4-03

•016

5150 )

la.

"\ f

4*2 and 4-35

•025

120

5120

13.

4-2 and 4-05

•021

126

6190

14.

R-9 and 5*8

•016

6300

V At\t\£k.

16.

'Crown-gUss •

6*0 and 6*3

•020

5290

r6000

I«.

4-1 and 7*0

•016

6360

17. J ^

4*0 and 7*0

•019

109

6900

}

Hence we have the tenacity of glass^ —

lbs. per sq. in.

T=4200, for flint-glass,

T=4800, for green glass,
and T=6000, for crown-glass.

The general equation (15), giving the bursting pressure
in pounds per square inch, then becomes —

P=4200 X -£, for flint-glass,

P=s4800 X -^, for green glass.

P = 6000 X "T- , for crown-glass.
A

For globes of uniform diameter and thickness these
formulse become —

94 ON THE MECHANICAL PROPERTIES OF GLASS,

P = 1 6,800 X :A, for flint-glass,

k
P= 19,200 X c^, for green glass,

P = 24,000 X ^, for crown-glass.

III. Generalisation of the Results of Experiments on the
Tensile and Compressive Resistances of Glass.

Mean tenacity (T^ of glass in the form of bars
=^2286-f2540-f2890H- 2540)= 2560 lbs. per sq. in. ;

Mean tenacity f T'J of glass in the form of thin plates
=^(4200-f4800 + 6000) =5000 lbs. per square inch;

T' 6000 ^ ,
Tf=2560='°^"^^^'

that is, the tenacity of glass in the form of thin plates is
about twice that of glass in the form of bars.
Mean resistance (Tg) of glass to compression

=^(27582 + 31876 + 31003)=30,150 lbs. per sq. in. ;

T, 30,150

__2— -

Tj 2560

= 11'8 nearly.

that is, the ultimate resistance of glass to a crushing force
is about twelve times its resistance to extension.

IV. Resistance of Rectangular Glass Bars to a Transverse

Strain.

Let 7= the length of the bar supported at the ends and
loaded in the middle.
'W'= breaking weight in lbs.

AND RESISTANCE OP GLASS VESSELS TO COLLAPSE. 95

K=area of the whole transverse section.
D=the whole depth of the section.
dy c^i = the respective distances of the top and bottom
edges from the neutral axis.
Tj = the tensile resistance of the material in lbs. per

square inch.
Tjsrthe compressive resistance of the material in lbs.
per square inch.
Then we have Tate's '^ Strength of materials," equa-
tions (27) and (6)—

W=|.3^^,andJ=5;

hence we get

w^4 TpTg K.D p KD ,.yv

^^'tT+t, 1 — / ' ' ^ ^

where the constant

C = ^. T^ =ix^^^^^^^^^ =3140 nearly.
^ T^ + Tj ^ 32710 ^

Substituting this value of the constant, equation (16)
becomes

W=3140^, .... (18)

which expresses the transverse strength of a rectangular
bar of glass supported at the ends and loaded in the
middle.

96 ON THE TENSILE STEENGTH OF

III.

RESEARCHES ON THE TENSILE STRENGTH OF WROUGHT
IRON AT VARIOUS TEMPERATURES.

(From the Report of the British Association for 1856.)

On a previous occasion I had the honour of conducting,
for the Association^ a series of experiments to determine
the effects of temperature on the strength of cast iron. In
that inquiry I endeavoured to show to what extent the co-
hesion of that material was affected by change of tempera-
ture, and taking into account the rapidity with which iron
imbibes caloric, and the facility wi4h which it parts with
it, it is equally interesting to know to what extent wrought
iron is improved or deteriorated by similar changes. In
the present inquiry, as in the former on cast iron, the
expansion of the metal by heat is not the question for solu-
tion. Rondelet, Smeaton, and others, have already inves-
tigated that subject, and it now only remains for us to
determine the effects produced on the strength of malleable
iron by changes of temperature varying from — 30*^ of
Fahrenheit to a red heat, perceptible in daylight.

The immense number of purposes to which iron is
applied, and the changes of temperature to which it is ex-
posed, render the present inquiry not only interesting, but
absolutely essential to a knowledge of its security under
the varied influences of those changes ; and when it is
known that most of our iron constructions are exposed to
a range of temperature varying from the extreme cold of
winter to the intense heat of summer, it is assuredly de-

WBOUGHT IRON AT VARIOUS TEMPERATURES. 97

sirable to ascertain the effects produced by these causes on
a material from which we derive so many advantages, and
on the security of which the safety of the public not un-
frequently depends.

Independent of atmospheric influences, another con-
sideration presents itself in reference to the durability and
ultimate stability of iron under changes much greater than
those alluded to above, and this is the strength of such ves-
sels as pans and boilers subjected to the extreme tempera-
tures of boiling liquids on one side, and the intense heat
of a furnace on the other. But even these extremes, how-
ever great, do not seem seriously to affect the cohesive
strength o{ wrought-iron plates, nor do they appear to
cause any disruption of the laminated structure which
results from the system of piling and rolling adopted in
the manufacture, excepting only where small particles of
scoria happen to intervene between the laminated surfaces.
These not unfrequently prevent a perfect welding, as the
plate is compressed by passing through the rolls, and the
effects of temperature are strikingly exhibited in the pro-
duction of large blisters upon the surface of the plate, as
shown in the annexed sketch at a, a. Now the reason of

Fig. 23.

this is the want of solidity and homogeneity in the plate,
and the consequent expansion of the lower part exposed
to the greatest heat. Let us suppose, for the sake of
illustration, the pljte to be f ths of an inch thick, and the
surface A to be the interior of a boiler-plate, and the sur-
face a, a to be exposed to the action of the fire in the
furnace. In this case it is evident that the temperature

98 ON THE TENSILE STRENGTH OF

of the side a, a may be upwards of 1000% while that of b
is very little above 212°, or the temperature of boiling
water ; and supposing there be any imperfection or want
of soundness in the plate, the result will be a greater
expansion on the exterior surface, causing it to rise up in
blisters in the manner we have described. These defects
are invariably present when the plates are not sound ; but
in other respects, where the bars which form the pile are
clear and free from rust or scoria, and are well welded in
the rolling process, the wide difference between the tem-
perature of one side and that of the other produces,
apparently, no injurious effect on the strength of the plate.
It is, however, widely different when the ^hole of the
plates are exposed to the same degree of temperature, as
in this position the strengths are increased or diminished
according as the temperature approaches or recedes from
the point where the strength is a maximum.

In order to show how the results were obtained, it will
be necessary to describe the apparatus and mode of con-
ducting the experiments.

The apparatus consisted of a powerful wrought-iron
lever, Plate III. A^Jigs. 2 and 3, capable of imparting a
force of more than 100,000 lbs., or 45 tons per square inch
to the specimen to be broken. The lever is supported in
a cast-iron standard or frame B, arranged for the reception
of specimens of the material to be subjected to a crushing
force or tensile strain. On the short arm of the lever the
plates amd b*rs (one of which is seen at a) were suspended
by a shackle e,'and held down to the bottom of the cast-
iron standard by the rod and screw e ; on this rod the box,
A, was fixed, and prepared to hold a bath of oil or water,
in which the iron to be broken was immersed. Below
this box was a fire-grate, rf, for heati^ the liquid in the
bath to the required temperature, and this grate could be
drawn backwards from the box, ft, when the required tem-

tMENTS

lICTH OF IRON.

WROUGHT IRON AT VARIOUS TEMPERATURES. 99

perature was attained or when it became too high. The
fulcrum of the lever is shown at fy and the scale in which
the weights were placed at g. The cast-iron standard
was firmly bolted to the heavy balks of timber upon which
it stands, and the pressure on the specimen was adjusted
by placing weights in the scale.

The plates experimented upon were of the form shown
in fig. 24, reduced at ay to 2\ inches wide, and at i to 2
inches wide, in order to secure fracture at the part of the

Fig. 24.

I
I

• m I

—6* — -^J^-a-i-x — 4--->J

— i^s/ ^

■

Fig. 25.

— — ■»- — i > ot ■ ■ — ■■—— — >*

plate immersed in the liquid in the bath. At each end
two holes are drilled to receive the bolts which fixed them
in the shackles. The wrought-iron bars were formed in a
similar manner. They were ^ inch in diameter, reduced
to I of an inch at a, and to -^ inch, or ^ inch at b. The
shackles were made to clasp the bars below the shoulders
so as to apply the strain requisite to cause fracture. It is
evident that the weakest part of the bars being within
the bath, breakage was sure to occur at that point where
the temperature was raised or lowered to the required
degree.

H 2

100

ON THE TENSILE STRENGTH OP

With these preparations, the experiments proceeded as
follows : — the bar to be broken was fixed between the
shackles of the lever; and, if necessary, the bath was
filled, and the fire drawn close under it ; as soon as the in-
tended temperature was attained, the lever was let down
by the crab, and weights carefully added to the scale until
the bar broke. During the process the temperature was
observed from time to time, and the fire adjusted accord-
ingly, and the temperature registered in the Tables was
observed immediately after the bar had given way.

Experiments to ascertain the Influence of Temperature on
the Tensile Strength of Boiler Plate,

Table I. — Strain applied in the direction of the fibre.
Boiler plate; sectional area =2*02 x '34 = '6868 sq. in.

Tempe-

No. of

Strain

Elonga-
tion in

Breaking weight

rature,

experi-

applied

per square inch

Remarks.

Fahr.

ments.

in lbs.

inckiet.

inltM.

0«>

18,540

For jQgures of the specimens

26,940

experimented on. see

27.780

Plate IV.. the uombering

28,620

of the figures corres-

29,460

ponding with that of the

30,300

tables.

31.140

Broke with a clear ringing

31,980

noise, almost like cast-

32,820

iron.

33.660

•14

49.009

= 21-879 tons.

The temperature in this experiment was reduced to
zero by a mixture of pounded ice and salt, carefully
placed round the plate in order to secure the same tempe-
rature in the metal as in the bath.

WROUGHT IRON AT VARIOUS TEMPERATURES. 101

Table II. — Strain applied across the fibre.
Boiler plate ; sectional area =2 '5 x '313 = '7825 sq, in.

Tempe-
rature,
Faiir.

No. of
experi'
ments.

Strain
applied
in lbs.

Elonga-
tion in
incties.

Breaking weight

per square inch

in lbs.

Remarks.

60°

1
2
3
4
5
6

8,190
10,140
16,860
23,580
30,300
31,980

•162

40,357

= 1 8*001 tons.

The experiments in the above and No. III. Table were
conducted at the temperature of the atmosphere. Both
specimens indicated a hard brittle iron, the interior lami-
nations having somewhat the appearance of cast iron^ with
a fracture widely different from that exhibited when torn
asunder in the direction of the fibre.

Table III. — Strain applied across the fibre.
Boiler plate ; sectional area =2'0 x '32 = '64 sq. in.

Tempe-

No. of

Strain

Elonga.

Breaking weight

rature,

experi-

applied
in lbs.

tion in

per square inch,
fn lbs.

Remarks.

Fahr.

ments.

inches.

60<>

10,140
(1680 lbs.
were added

Some steely spots in

•

at a time
till weight

fracture.

25,260

26,100

26,940

27,780

•1

43,406

= 19-377 tons.

H 3

102

ON THE TENSILE STRENGTH OF

Table IV.— Strain applied In the direction of the fibre.
Boiler plate ; sectional area =1*99 x '32 = '6368 sq. In.

Tempe-
rature,
Fahr.

60°

No. of

Strain

Elonga-
tion in

experi-

applied

ments.

in lbs.

inches.

10,140

18,540

20,220

21,900

23,580

25,260

26,100

8 ,

26,940

27,780

28,620

29,460

30,300

31,140

31,980

•2

Breaking weight
per square inch
in lbs.

50,219

Remarks.

A fissure containing cin-
der extended one-third
of the breadth of the
plate. In some parts
the blade of a penknife
could be introduced.

» 22*414 tons.

In some former experiments on the tensile strength of
wrought-Iron plates *, the strength of the specimens was
rather more uniform, and there appeared to be no differ-
ence between the strength of the plates when torn asunder
In the direction of the fibre, and the strength when the
strain was applied across It. Comparing Tables II. and
III. with IV., we find the breaking weight In the direction
of the fibre Is to that across It as 22-41 : 18'67, or as 5 : 4
nearly ; but It Is possible that this arises from Inequality
in the rolling of the two specimens.

* Philosophical Transactions for 1850, p. 677, the results of which are
also giren in ** Useful Information,** First Series, Appendix I.

WBOUGHT lEON AT VARIOUS TEMPEBATURES. 103

Table V. — Strain applied across the fibre.
Boiler plate ; sectional area = 1*99 x '33 sq. inch.

Tempe-
rature,
Fahr.

No. of
experi-
ments.

Strain
applied
in lbs.

Elonga-
tion in
inches.

Breaking weight

per square inch

in lbs.

Remarks.

110<^

1
2
3

4
5

25.260
26^940
27,780
28,620
29,460

•13

44,160

Fracture very uneven.

«19-714ton8.

The last weight was hardly
on: 29,000 lbs. was
probablj nearer the
breaking weight.

Table YL — Strain applied in the direction of the fibre.
Boiler plate; sectional area =2*0 x '34 = '68 sq. inch.

Tempe-

No. of

Strain Elonga.
applied tlon in

Breaking weight

rature,

experi-

per square inch

Remarks.

Fahr.

ments.

in lbs.

inches.

in lbs.

112<^

1
2
3
4
5
6

18,540
20,220
21,900
23,580
25,260
26,940

28,620

42,088

= 18*789 tons.

a 4

104

ON THE TENSILE 8TBEN6TH OF

Table VII. — Strain applied in the direction of the fibre.
Boiler plate ; sectional area =2*54 x *32= '8128 sq. inch.

Tempera-

ture,

Fahr.

No. of
experi-
ment*.

Strain

applied

in lbs.

Elongation
in inches.

Breaking weight

per square inch

inlbv.

Remarks.

120<>

1
2
3
4
5
6
7
8
9

10
11
12
13

25,260
26,940
28,620
30,300
31,140
31,980
32,400
33,660
34,500
35,340
35,760
36,180
36,600

37,020

•173

40,625

== 18*136 tons.

The last three experiments^ at a mean temperature of
114°, indicate a near approach to uniformity of strength,
that broken across the fibre being the strongest ; the very
reverse of those fractured at 60®, the numbers being as
197 : 184, or as 44 : 41 nearly, showing a loss of about
•007 per cent. It is difficult to account for these changes
and defects in the strengths of the plates, as most of the
specimens were cut from one plate, and all of them were
of the same manufacture.

Table VIII. — Strain applied in the direction of the fibre.
Boiler plate; sectional area =2*6 x '308 = '8008 sq. inch.

Tempera-
ture,
Fahr.

Naof
experi-
ments.

Strain

applied

in lbs.

Elongation
in inches.

Breaking weight

per square inch

in lbs.

Remarks.

212<>

1
2

30,300
31,980

•15

89,935

= 17^828ton8.

WROUGHT IRON AT VARIOUS TEMPERATURES. 105

Broken in boiling water. This specimen did not break
at the narrowest part of its section^ which shows a serious
defect in the plate.

Table IX. — Strain applied across the fibre.
Boiler plate ; sectional area =2*01 x '33 = '6633 sq. inch.

Tempera-

No. of

Strain

Elongation
in inches.

Breaking weiglit

ture,

experi-

applied

per square inch

Remarks.

Fahr.

ments.

inltNi.

in lbs.

212«>

18.540

Broken in boiling

•

2
3

20,220
21,900
23,580

water.

25,260

26.940

27,780

28,620

29,460

■

30,300

•11

45,680

» 20 -392 tons.

In Table VIII., where the specimen was drawn in the
direction of the fibre, there appears to be some defect in
the plate, as it gave way, not at the smallest section, but
at a wider part of the plate, with a force of only 39,935 lbs.
to the square inch, whereas the same plate torn asunder
across the fibre sustained a force of 45,680 lbs. before
breaking. This difference of strength can only be ac-
counted for by some defect not perceptible when the frac-
ture was examined. The difference of strength, at the
temperature of boiling water, indicated by these two
specimens, is as 178 : 203^ or in the ratio of '87 : 1.

106

ON THE TENSILE STRENGTH OP

Table X, — Strain applied in the direction of the fibre.
Boiler plate ; sectional area =2*0 x •34 = *68 sq. inch.

Tempera-

No. of

Strain

Elongation

in in^hpft-

Breaking weight

ture.

experi-

applied

per square inch

Remarks.

Fahr.

ments.

in lbs.'

lU 1 U V U V V •

in lbs.

212°

18,540

Broken in boiling

20,220

water.

21,900

23,580

25,260

26,940

27,780

28,620

29,460

30,300

31,140

31,980

32,820

33,660

•22

49,500

=^22*098 tons.

Comparing this plate with that in experiment VIIL^Jt ^^
will be seen that the power of resistance of the former is'^V'^
more than one fifth greater than that of the la^er^ showing
that there must have been some defect in the longer
section of the specimen, or fracture would not have ensued
at so early a period of the experiment. We cannot aban-
don this experiment, as no defect presented itself, if we
except the highly crystallised state of the fracture, both
specimens having been drawn asunder in the direction of
the fibre. In these experiments it will be observed that
the infusion of heat into wrought-iron plates, from zero to
212°, does not injure^ but rather improves^ their tensile
strength.

WEOUGHT IRON AT VAEIOUS TEMPERATURES. 107

Table XI. — Strain applied In the direction of the fibre.
Boiler plate; sectional area =2*01 x *32 = *6432 sq. inch.

Tempera-
ture,
Fahr.

No. of
experi-
ments.

Strain

applied

in lbs.

Elongation
in inches.

Breaking weight

per square Inch

in lbs.

Remarks.

270°

1
2
3
4
5
6
7
8

18,540
20,220
21,900
23,580
25,260
26,940
27,780
28,620

•13

44,020

Broken in hot oU.

Broke before the last
weight was fairlj
on; 28,320 lbs. pro-
bably nearer.
» 19*651 tons.

From this experiment it appears that an increase of 58^
of heat makes no perceptible difference in the strength of
the plate. If we take the mean of the two previous
experiments^ in the direction of the fibre^ it will be found
there is no great difference between them, the mean of
Tables VIII. and X. being 44,708, and Table XL giving
44,020 lbs. to the square inch.

Table XII. — Strain applied in the direction of the fibre.
Boiler plate; sectional area =2*0 x *32 = *64 sq. inch.

Tempera-
ture,
Fahr.

No. of
experi-
ments.

Strain

applied

in lbs.

Elongation
in inches.

Breaking weight

per square inch

in lbs.

Remarks.

340®

1
2
3

4
5
6
7

25,260
26,940
28,620
29,460
30,300
31,140
31,980

•1

49,968

B 22*307 tons.

108

ON THE TENSILE STRENGTH OP

In this experiment the plate gave way at the shackle^
the bolt which held the plate tearing through the eye, and
forcing away a four-sided piece as the plate was about to
yield to the weight on the lever. We may therefore safely
assume 31,980 or 32,000 lbs. as the ultimate strength or
breaking weight of the plate.

Table XIII. — Strain applied across the fibre.
Boiler plate; sectional area =2*0 x '34= '68 sq. inch.

Tempera-
ture, '
Fahr.

No. of
experi-
ments.

Strain

applied

in Ibft.

Elongation
in inches.

Breaking weight

per square inch

in lbs.

Remarks.

340°

1
2
3

4
5
6
7
8

18,540
20,220
21,900
23,580
25,260
26,940
27,780
28,620

•15

42,088

Broken in hot oil.
«18'789 tons.

The mean result of experiments XII. and XIII. is
46,014 lbs., or about 20J tons per square inchj evidently
showing that the iron is in no degree injured by a tempe-
rature ranging from zero up to 340^ and this temperature
may probably be increased as high as 500"* or 600^ without
seriously impairing the strength, as may be seen in the
following Table at nearly 400**.

WROUGHT IRON AT VARIOUS TEMPERATURES, 109

Table XIV. — Strain applied in the direction of the fibre.
Boiler plate; sectional area =2*02 x 'SS^'6666 sq. inch.

Tempera-

No. of

Strain

Elongation
in inches.

Breaking weight

ture,

Fahr.

experi-
ments

applied

per square inch
in lbs.

Remarks.

395*^

1
2
3
4
5
6
7
8
9

10
11
12

18,540
20,220
21,900
23,580
24,420
25,260
26,100
26,940
27,780
28,620
29,460
30,300

•

Broken in hot oil.

'30,720

•18

46,086

= 20-574 tons.

The only difference between this and the last two ex-
periments is the increased elongation^ which in the latter
was 1*25, and in the former '18 inches. However, the
elongation of these short specimens cannot always be de-
pended on, as there is considerable difficulty in ascertaining
them accurately.

Table XV. — Strain applied across the fibre.
Boiler plate, sectional area= 20 x '31 = 62 sq. inch.

Tempera-

No. of

Strain

Elongation
in inches.

Breaking weight

ture,
Fabr.

experi-
ments.

ris^

per square inch
in ibs.

Remarks.

8,190

A scarce-

10,140

ly per-

11,820

ceptible

13,500

red heat

5
6

7
8
9

15,180
16,860
18,540
20,220
21,900

23,520

•15

38,032

s 16-978 tons.

110 ON THE TENSILE STRENGTH OF

The plate in this experiment was heated until it became
perceptibly luminous in the shade ; it was then loaded, as
before, until fracture ensued. In this experiment it will
be observed that a considerable diminution of strength
took place in consequence of the increased temperature,
clearly showing that above a certain point the tensile
strength of wrought iron is seriously injured. This fact
is more strikingly apparent in the next experiment, in
which the temperature was raised to a dull red heat, just
perceptible in daylight.

Table XVL

In this experiment a plate of the same description as
the last was raised to a dull red heat, when the weight of
the lever was allowed to strain the specimen with a force
of 18,540 lbs., and fracture immediately ensued. The
elongation was *23.

Sectional area of boiler plate =1*96 x '31 = '6076 sq.

inch.
Strain applied across the fibre.
Breaking weight per square inch = 30,513 ]bs. = 13*621

tons.

This experiment is quite conclusive as to the effects
produced on wrought iron whenever it approaches a red
heat. At that temperature nearly one half its strength is
lost ; it becomes exceedingly ductile, and is drawn con-
siderably in the direction of the strain before its cohesive
powers are destroyed.

The greatly increased ductility of wrought-iron plates,
at a dull red heat, is strikingly exemplified in the flues of
boilers, whenever the water gets low, or recedes below
the surface of the plates, and that more particularly if the
plates are immediately over the fire ; in such a position
the flues readily collapse with a comparatively low pres-

WBOUGHT IRON AT VARIOUS TEMPERATURES. Ill

sure. In the bending of a plate^ when red hot, a very
small force is required ; but within limits of temperature
not exceeding 400°, it requires nearly the same force to
produce collapse as it would at any temperature above 32"^,
or the freezing point of water.*

Collecting the results of these experiments, tabulated
above, it will be necessary to exhibit them in a more con-
densed form, so as to facilitate comparison, and to deduce
the laws which regulate the tensile strength of wrought
iron. We may then apply the results of these experi-
ments to a much greater variety of plates produced in the
different districts of England. It will be borne in mind

General Summary of Results.

No. of
expert-

Breaking
weiKht
in lbs

Breaking

Breaking 1

Mean break-

Direction of

Temperature,
Fahr.

weiglit per

ing weight

strain in

square incli

per square

regard to

UlCtll*

lU IVB*

in lbs.

in tons.

inch in lbs.

flbre.

0°

33,660

49,009

21-879

49,009

With.

II.

31,980

40,357

18 001

Across.

III.

27,780

43,406

19-377

. 44,498

Acros8.f

IV.

31,980

50,219

22-414

With.t

110

29,460

44,160

19714

•

Across §

VI.

112

28,620

42,088

18-789

. 42,291

With.

VII.

120

37,020

40,625

18136

With.

VIII.

212°

31,980

39,935

17-828

With.§

IX.

212

30,300

45,680

20-392

. 45,005

Across.

212

33,660

49,500

22098

With.

XI.

270

28,620

44,020

19-651

44,020

With.

XIL

340

31,980

49,968

22307

j 46,018

With. 11

XIII.

340

28,620

42,088

18-789

Across.

XIV.

395

30,720

46,086

20-574

46,086

With.

XV.

Scarcely red

23,520

38,032

16-978

► 34,272

Across.

XVL

Dall red

18,540

30,513

13,621

Across.^

* We hope in a short time to give a series of experiments on the resist-
ance of wronght-iron plates and bars to a transverse and compressive force
at variooB temperatnres. :|: Fissnre containing scoria.

f Some steelj spots in fracture. (| Too low, tore through the eye.

§ Too high, fracture very uneven. % Too high, see Table.

112

ON THE TENSILE STRENGTH OP

that the ordinary Staffordshire plates^ such as those ex-
perimented upon (unless they are double- worked), are
rather inferior in quality to the Shropshire and Derby-
shire plates, and much more so to those manufactured at
the Lowmoor and Bowling works. Hence the com-
parison will only hold good between the StaflPordshire
plates in each case.

From the above Table we may deduce the following: —

Tempera-
ture,
Fahr.

Drawn asunder in the direction of
the fibre.

Drawn asunder across the fibre.

Breaking weight

per square inch

in lbs.

Breaking weight

per square inch

in tons.

Breaking weight

per square inch

in lbs.

Breaking weight

per square inch

in tons.

0°
60
114 *
212
270
340
395
Bed

49.009
50,219
41,356
44,717
44,020
49,968
46,086

21-879

22-414t

18-462

19-963§

19-651

22-307

20-574

41,881
44,160
45,680

42,088

34,272

18-689*
19-714$
20-392

18-789

15-299lf

From the experimental inquiry into the strength of
wrought-iron plates, as applied to ship-building, we have
the following results: — **

* Some steely spots in fractare.

f Fissare containing scoria.

J Too high, fracture very nneyen.

§ Did not break at the smallest section.

II Too low, tore through the eye.
% Too high, see Table.
** Useful Information, First Series, Appendix L

WROUGHT IRON AT VARIOUS TEMPERATURES. 113

Mean breaking Weight,
in the direction of the
Fibre, in tons per
•quare inch.

Mean breaking Weight,
across the Fibre, m
tons per square inch.

Yorkshire plates .
Yorkshire plates .
Derhyshire plates
Shropshire plates
Staffordshire plates

25-770
22-760
21-680
22-826
19*563

27-490
26-037
18*650
22-000
21-010

Mean • •

22-519

23-037

Now if we compare the ultimate strength of the Staf-
fordshire plates in the above Table with those since
experimented upon, we shall haye> taking those in which
the strain was applied in the direction of the fibre, for the
former 19*563 tons per square inch, and for a mean of
nine experiments of the latter, ranging in temperature
from zero to 395**, 20*408 tons per square inch. Taking
those torn asunder across the fibre, we have for Stafford-
shire plates in the above Table 2 10 10, and for those since
experimented on 19*254 tons* per square inch, which on
comparison give the following ratios of results : —

Staffordshire plates, torn in the direction of the fibre, at
a mean temperature of 191° =20*408 tons, and those (in
the above Table) at the temperature of the atmosphere, or
about 60°= 19*563 tons, or in the ratio of 1*: '96 nearly, a
close approximation in tensile strength in the two series
of experiments.

Those torn across the fibre, at a mean temperature of
156**, gave a tensile strength =19*254 tons; those at the
temperature of atmosphere 60% as shown in the previous
experiments=21*010 tons, or in the ratio of 1 : 1*091.

* The mean temperature of nine speeimenfi, broken in the direction of
the fibre, is 19 1^'; and the mean temperature of five, broken across the
filjre, excluding red heat, is 156®.

114 TENSILE STRENGTH OF RIVET IKON.

The above results indicate great uniformity In the ulti-
mate strength of Staffordshire plates, which may safely be
taken at 20 tons per square inch at all temperatures,
between the extremes of zero and 400*^ Fahr., that is,
under a dead weight calculated to destroy the cohesive
powers of the material. To what extent these plates
would resist impact, at various degrees of temperature, we
have yet to determine; but assuming that iron is more
liable to fracture from an impactive force at a very low
temperature, it will be safer to calculate on a reduction of
their resisting powers, at the lower temperatures under
32** Fahr., or the freezing-point of water.

These experiments might be multiplied to a great
extent, in order to determine the strength of plates under
the varied conditions of temperature in regard to com-
pression, extension, and the force of impact ; but we have
already shown in former experiments, and those now
recorded above, that iron is not seriously affected by those
changes, and we trust the foregoing results will prove suf-
ficient to enable the practical engineer to calculate the
resisting powers of iron plates, under all the changes of
temperature, from zero up to a red heat.

In Plate IV. will be found drawings of most of the
fractured surfaces of the boiler plate, numbered to cor-
respond with the preceding tables.

. Experiments on the Tensile Strength of Rivet Iran.

At the time when the preceding experiments were
instituted, it was considered expedient to make them on
plates of ordinary quality, and of the description in general
use. For this purpose Staffordshire plates were selected,
as being of medium quality, such as are employed in the
construction of boilers, ship-building, &c. Plates of a
higher character, such as the Lowmoor and double-worked

FlaZelV

"^00^..

>-t.-iJI^M.

^ '-m.i _iL

Za-pejiiiient 1

Xxjcperiment,

TENSILE STRENGTH OF EI VET IBON. 115

qualities, might have been selected; but those most in
demand, and which are manufactured in large quantities,
were considered more desirable, although it left untouched
a question of some importance in regard to the influence
of heat upon the finer qualities, generally known as
" scrap " and ^^fagotted^^ iron. This description of iron is
forged from old iron scrap, and rolled into bars for bolts
and rivets. It is a fine ductile iron of great tenacity, and
works freely under the hammer ; and it was determined
to apply to it the same experimental tests as had been
applied to the Staffordshire plates.

From the results of these experiments, it will be seen
that they indicate precisely the same law as was found to
influence the Staffordshire plates^ the maximum strength
being at a temperature of 325^ rather higher than that
indicated by the plates. This is irrespective of the supe-
rior strength of the bar iron as compared with that of the
plates.

Having prepared the lever, as before, a long bar, ^ths
of an inch in diameter, was selected and cut into lengths,
which were then reduced to the form shown in the

Fig. 26.

annexed sketch, with shoulders to receive the shackle.
The specimens, when immersed in the bath, were drawn
asunder by the same process as that described for the
plates.

I 2

116

TENSILE STRENGTH OF RIVET IRON.

Experiments to ascertain the Influence of Temperature
on the Tensile Strength of Rivet Iron.

Table XVIL — Area of 8ectioii='2485 sq. ins.

Tempe<

No. of

Strain

Elonga-

Breaking Weight

rature,

Expert.

applied

tion in

per square inch
in lbs.

Remarks.

Falir.

ments.

in lbs.

inches.

-30°

9,205

Broken in a mixture of

9,415

pounded ice and crys-

11,648

tallised chloride of
calcium.

10,045

♦ ♦ « «

Figures of some of the
fractured 'specimens

15,610

will be found in Pi. IIL
fig. 1, numbered to
correspond with the
tables.

15,715

•80

63,239

:s28-2dl tons.

From the above it will be observed that the strength of
the best quality of bar iron greatly exceeds that of the
plates, being in this experiment two-fifths' more, and in
Bome experiments^ at higher temperatures^ nearly double
that of the Stafibrdshire plates.

Table XVIII. — Sectional area=*2485 sq. ins.

Tenipe.
rature,
Fahr.

No. of
Experi-
ments.

Strain

applied

in lbs.

Elonga-
tion in
inches.

Breaking Weight

per square inch

in ibs.

Remaxks.

+ 60°

1
2
3

12,565
13,405
13,812

14,035

* « • *

15,295

15,400

•82

61,971

A large bright spot, like
steel, in fracture.

«27*665 tons.

There is a slight diminution in llie strength of this bar
as compared with the previous experiment at— 30% but

TENSILE STRENGTH OF RIVET IRON.

117

the discrepancy is scarcely appreciable^ and may easily be
accounted for by inequalities in the forging or rolling of
the bar.

Table XIX. — Sectional area=:*2485 sq. ins.

Tempe

rature,

Fabr.

No. of
Experi-
ments.

Strain

applied

in lbs.

Elonga-
tion in
inclies.

Breaking Weight

per square inch

in lbs.

Itomarks.

60<>

1
2
3

30
31

9,415

10,255

12,565

12,985
♦ « * •

15.715
15,820

•56

63,661

Drew out at shoulder.
-« 28*419 tons.

The strength of the bar in this experiment is a trifle in
excess of those fractured at— 30° and 60**. It would have
been rather stronger had it been rounded at the shoulder
like the others to prevent its pulling out there^ as shown in
the figure. However, there is little diflference in the strength
of the material through a range of 90** of temperature.

Table XX — Sectional area = '2485 sq. ins.

Tempe-
rature,
Falir.

No. of
Expert,
ments.

Strain

applied

in ItM.

Elonga-
tion in
incites.

Breaking Weight

per square inch

in lbs.

Remarks.

114®

1
2
3

10,885
12,565
13,405

13,615

« « * «

•

Pulled out at shoulder.
After between 13,000
and 14,000 lbs. had
been laid on, onlj
105 lbs. were added

17,500

at a time, as it gave
more correct indica-
tions of the strength
as the bars approached
fracture.

17,605

•56

70,845

s 31*627 tons.

Z 3

118

TENSILE STRENGTH OF RIVET IRON.

It has already been observed that the whole of the
specimens for experiment were cut from one bar, and as
each experiment was conducted with great care, both in
preparing the specimens and laying on the weights, we
are bound by the results to believe that the increased
strength of this description of iron is due entirely to the
increase of temperature. In this experiment it will be
seen that the resisting power of the bar ruptured at 1 14**
was to that of the bar ruptured at 60"^ (Table XIX.) as
1 : -898.

Table XXL — Sectional area=*2485 sq. ins.

Tempe-

No. of

Strain

Elonga-

Breaking Weight

rature,

Experi-

applied

tion in

per square inch

Remarks.

Fahr.

ments.

in ibs.

inches.

in lbs.

212<^

12,565

2
3
4
5

12,985

13,405

13,825

14,245
« « * *

21,805

At this point it was disco-
vered that the bar was
cutting into the shackle;

12.565

the experiment was

12,985

therefore discontinued

13,405

till a new shackle could

13,826
* • « «

be prepared, and it was
then repeated.

19,285

•64

Meai

1 . .

20,545

82,676

= 36*900 tons.

This bar tore into the shackle^ so that the strain was
not thrown properly on it ; the experiment was therefore
discontinued^ and another shackle substituted with the
bearing-edges steeled. When the same bar was tried
again^ having been injured in the previous experiment, it

TENSILE STRENGTH OF RIVET IRON.

119

broke with 1 9^2851 bs. Under these circumstances^ we have

. 1 ., P ,, . . . 21,805 + 19,285
taken the mean of the two experiments, — — - —

= 20,545 as the breaking weight, as recorded in the
Table.

Table XXII.

— Sectional area:

= •19635 sq. ins.

Tempe-
rature,
Fahr.

No. of
Experi-
ments.

Strain

applied

inlbi.

Elonga-
tion in
inches.

Breaking Weight

per square inch

in lbs.

Remarks.

212<^

1
2
3

4
5
6

12,565
13,405
14,245
14,?»50
14,455
14,560

•47

74,153

Bar defective: a large
longitadinal fissure,
filled with scoria.

=33*104 tons.

There is a progressive increase in the strength of the
bars as the temperature ascends. Table XX. exhibiting an
increase of 1 1,831 lbs., and Table XXII. an increase of
3308 lbs. over the breaking weight at 1 14^ Taking the
mean of the two last experiments, we have an increase of
7569 lbs. over the breaking weight in Experiment XX.

Table XXIII. — Sectional area=*2485 sq. ins.

Tempe-
rature,
Fahr.

No. o(
Experi-
ments.

strain

applied

in lbs.

Elonea.
tion iu
inches.

Breaking Weight
j>er square inch
in lbs.

Remarks.

2120

1
2
3

39
40

14,245
15,925
16.135

16.345

* * * •

20,020
20,125

•66

80,985

» 36*154 tons.

This experiment being at the same temperature as the
two last, viz. 212% it will be proper to take the mean of

I 4

120

TENSILE STRENGTH OP RIVET IRON,

the last three Tables as the breaking weight at that tem-

82,676 + 74,153 + 80,985 >,oo*7iik
perature, — — ^ — -^ = 79,27 libs, per square

inch = ultimate breaking weight at 212^

Table XXIV.— Sectional area= '19635 sq. ins.

Tempe-
rature,
Fahr.

No. of
Experi-
ments.

Strain

applied

in lbs.

Elonf^a-
tion in
inches.

Breaking Weight

per square inch

in lbs.

Remarks.

250*='

1
2
3

10,045
10,885

11,725

« * « •

15,925
16,135

•6

82,174

» 36*684 tons.

Here again, in the above experiment, is a perceptible
increase of strength, as the temperature rises 38^ from
79,271 to 82,174 lbs. per square inch, and so in the next
Table, where the increase is still greater.

Table XXV. — Sectional areas=*2485 sq. ins.

Tempe-

No. of

Strain Elonga-

Breaking Weight

rature,

Experi-

applied

tion in

per square inch

Remarks.

Fahr.

ments.

in lbs.

inches.

in lbs.

270°

1
2
3
4
5
6
7

12,565
13.405
14,245
15,085
15,400
15,925

16,345

« • * «

20,545

20,650

•74

86,056

« 38*4 17 tons.

The increase of 20® of temperature in this experiment,
gives a corresponding increase of strength of 3882 Ibe.

TENSILE STRENGTH OF RIVET IRON.

121

per square inch^ something more than the increase exhi-
bited in the previous experiment. There is, however, a
remarkable coincidence in the ratio of the strengths as
they rise with the increase of temperature, the only excep-
tions being those of Tables XVII. and XXIL, but in both
cases the anomaly is sufficiently explained by the state of
the fracture.

Table XXVI. — Sectional area=:*19635 sq. ins.

Tempe-

No. of

Strain

Elonga-

rature,

Experi-

applied

tion in

Fahr.

ments.

iu lbs.

inches.

310<>

12,.565

14,245

15,085

15,295

15,715

15,820

•63

Breaking Weight

per square inch

iu lbs.

80,570

Remarks.

= 35*968 tons.

In this experiment it will be observed that there is a
falling off in tenacity with the increase of temperature
from 86,056 to 80,570 lbs. per square inch. It is difficult
to account for this discrepancy, as the fracture in this,
as in the pTevious and succeeding experiments, appeared
sound and free from flaws of any description.

Table XXVII. — Sectional area= '19635 sq. ins.

Tempera-
ture,
Fahr.

No. of
Experi-
ments.

Strain

applied

inibs.

Elongation
in inches.

Breaking Weight

per square inch

in lbs.

Remarks.

325«>

1
2
3

53
54

10.045
10,&85
11,725

17,080
17,185

•6

87,522

=39*072 tons.

122

TENSILE STRENGTH OP RIVET IRON.

The above bar, although of the same quality and
appearance as that in the previous experiment, gives no
less than 6952 lbs., upwards of three tons, greater tenacity
than its predecessor. The former appeared equally tough
and fibrous in the fracture, and the elongation in the same
distance was rather more than in the latter, and yet it is
about one-twelfth weaker.

Table XXVIIL — Sectional area=*2485 sq. ins.

Tempera-

No. of

Strain

Elongation
in inclies.

Breaking Weight

ture,
Fahr.

Experi-
ment*.

applied
in lbs.

per square inch
in lbs.

Remarks.

415°

i
2
3

4
5

12.5f5
14,245
15,085
15,925

16,765

• «*«

20,230

20,335

•64

81,830

s 36,531 tons.

In this experiment there is a decrease in the strength
with an increase of temperature of 90**, but fn the next
experiment, with a further increase of 20% the strength
again rises from 81,830 to 86,056, or nearly two tons,
which shows that the increase of 100® of temperature has
not seriously affected the molecular constitution of the
iron. This irregularity, after so constant an increase of
strength, indicates that we have about reached the maxi-
mum strength of the material. We shall see hereafter
that the increase of strength from — 30** to 325** has been
four-tenths, nearly one-half.

TENSILE STRENGTH OF RIVET IRON.

123

Table XXIX. — Sectional area='2485 sq. Ins.

Tempera-

No. or

Strain

Elongation

in liichAfl

Breaking Weight

ture,

Kxperl-

applied

per square incii

Remarks.

Fahr.

ments.

in Ibf .

in lbs.

435°

1
2
3
4

5
6

12,565
13,405
13,812
14,035
14,245
14,665
15,085

21,280

21,385

•74

86,056

= 38*415 tons.

The difference between this and the last experiment is
about one-eighteenth part of the former in favour of the
latter. This difference we cannot account for by an exa-
mination of the fractures ; but taking the mean of the
two, and comparing it with Table XXVIL, it appears
that we have passed the maximum strength^ and recede
from it in the ratio of 87,522 : 83,943, or as 1 : -959.

Table XXX. — Sectional area = -2485 sq. ins.

Temperature raised to red heat, visible by daylight.
Broke with the weight of the lever =8965 lbs.
Elongation = '55.

Breaking weight per square inch =36,076 lbs. = 16*105
tons.

In this experiment, as in those on the plates, the
tenacity of the iron is seriously injured before the tem-
perature reaches dull red heat ; and when that point is
attained, it has lost more than one-half its powers of
resistance to strain. At this high temperature it becomes
exceedingly ductile and weak when subjected to any

124

TENSILE STRENGTH OP RIVET IRON.

description of force^ inasmuch as it becomes so pliable
that it is immaterial whether the strain applied is com-
pressive, tensile, or torsional. Under any of these forces
it is not to be depended upon at a temperature bordering
upon redness.

Collecting the results of the foregoing experiments in
their consecutive order into a Table, we see that the
maximum strength of bars appears to be attained at a
(r- unv ^^^^^ temperature of about 320**, This is "ehov^ the
temperature at which the maximum strength of the plates
was attained; but it is to be remembered, that little
change is observable in the strength of the plates, whilst
that of the bars is increased nearly one-half.

This fact is worthy of notice, inasmuch as in countries
where the climate is hot and never descends below freez-
ing, the best bar iron will retain a power of resistance
equal to 29 tons upon the square inch, whereas in colder
and more northerly districts it would not be safe to calcu-
late upon more than 28 tons to the square inch.

General Summary of Results.

Temperature,
Fahr.

No. of
experi-
ment.

Breaking

Wd«ht

inlba.

Elon-
gation

in
inches.

Breaking

Weight per

square inch

in lbs.

Breaking

Weight per

square inch

in tons.

Mean break-
ing Weight
per square
bichinlbtf.

Bemarks.

-38

XVII.

15,715

•80

63,239

28-231

63,239

Too low.

+60
60

XVIII.
XIX.

15,400
15,820

-82

61,971
63,661

27 665
28^4 19

J 6-2,816

Too low.

114

XX.

17,605

•56

70,845

31 6'/7

70,845

Too low.

219

XXI.

20,545

•64

87,676

86 9(>0

> 79.271

212

XXII.

14,560

•47

74.153

33^I04

212

XXIII.

20,125

•66

80.()85

36154

250
270

XXIV.
XXV.

16,135
20,650

•60
•74

82,174
83,098

36-684
38-417

1 82,636

810
325

XXVI.
XXVII.

15,820
17,185

•63
•60

80,570
87,522

35-968
39 072

{84,046

415
435

xxvui.

XXIX.

20,335
21,385

•64
•74

81,830
86,0')6

36-.')3l
38-415

(83,943

Red heat.

XXX.

8.965

•55

86,076

16105

3\000

Too high.

In the above Table we perceive a steady improvement
in the strength of the iron from 60° up to 325% where the

TENSILE STRENGTH OF RIVET IRON.

125

maximum appears to be attained. As already noticed,
this improvement does not present itself in the inferior
descriptions of irons^ such as the plates tested in the pre-
ceding experiments. This may arise from the different
processes pursued in the manufacture, the bars being ren-
dered fibrous and ductile, in thq first instance, under the
hammer, and this is further improved by reheating them
and passing them between the rolls. Bar iron will thus
be drawn by the hammer and rolls to from twenty to
twenty-five times its original length ; whilst plates, such as
we have selected, never come under the hammer, and seldom
exceed six or eight times the length of the original
shingle after passing through the rolls.

On comparing these results with those of a similar
quality of iron, viz. S.C. ^ bar iron, experimented upon
at Woolwich Dockyard, it will be found that a corres-
ponding and progressive increase of strength is equally
apparent as in the above experiments ; that increase,
however, arising from a different cause, namely, the re-
peated fracture of the bars as exhibited in the following
Table : —

Fint Breakage.

Second
Breakage.

Thiid
Breakage.

Fourth
Breakage.

TtediioAd

Mark.

fipom
1*87

Stretch

Tom.

in 54
inches.

Tom.

in 36
inches.

Tons.

in 24
inches.

Tons.

in 15

inches.

in.

33-76

9- 125

35*5

2*00

33*75

9-250

85*25

•25

37*00

100

38'76

1-25

32-5

9 250

34-75

1*25

3.3*35

10-500

36-50

1*12

37-25

•62

40^40

• •

118

32*76

8-600

35-00

1-25

37-5

• t

40 41

• •

1*25

33*75

10*625

36-25

187

33*50

8-375

34 50

•0-2

36 5

1 50

Si'.M)

9-2iV0

36 00

36*75

1*120

41 -7S

• •

1*26

32-25

Defective

36-50

1*5

37-75

• •

41*00

•31

1*25

30*25

Defective

36*50

•62

3775

0-6

38-50
4016

•06

1-25

Mean . . .

32-92

t • •

35-57

• •

8721

• •

1*24

Mean per 7
square inch j

ilttai

• • •

23*86

• t

27*06

• •

29*20

•

•90

,tH

^s.l^

126 TENSILE STRENGTH OF RIVET IRON.

From the above it will be seen that the mean strength
of the bars was 24 tons, whilst that of the rivet iron was
28 tons per square inch, at a temperature of 60% and that
the former attained its maximum strength of 29 tons from
repeated breakages, whilat the latter reached a strength of
37 tons by an increase of temperature up to 317^ These
are curious and interesting facts, exhibiting a parallel in-
crease of strength, in the one case resulting from repeated
strains, in the other from increase of temperature.

The foregoing Table indicates a progressive increase of
strength, notwithstanding the reduced sectional area of the
bars. This fact is of considerable importance, as it shows
that a severe tensile strain is not injurious to the bearing
powers of wrought iron, even when repeated to the
extent of four times. In practice, it may not be prudent
to test bars and chains to their utmost limit of resistance ;
it is however satisfactory to know, that in cases of emer-
gency those limits may be approached without incurring
a serious risk of injury to the ultimate strength of the
material.

It is further important to observe, that the elongations
are not in proportion to the forces of extension ; thus in
the bar ^ the elongation of a bar, 54 inches long with
33*25 tons, is 10*5 inches^ giving an elongation per unit

of weight and length = ^ ^ — —• =-0058, whereas an

additional weight of 2*25 tons produces an elongation of
l*!di5 inches in 36 inches of length of bar, giving an elonga-
tion per unit of length and weight =^;^- — ^= -0154;

that is, the elongation in this case is about three times that
in the former.

From the experiments on rivet iron we have a mean
elongation, in fourteen experiments, of '643 inches in 2^

TENSILE STRENGTH OF RIVET IRON.

'643

127

inches, or -jr^= '257 per unit of length ; and in those on

the S.C. ^ bars, we have a mean elongation of '274, as
given in the following Table : —

Length of Bar.

Elongation.

Elongation per Unit
of Length.

in.
120
42
36
24
10

260
9-8
8*8
62
4*2

•

•216
•233
•244
•258
•420

Hence it appears that the rate of elongation of bars of
wrought iron increases with the decrease of their length ;
thus while a bar of 120 inches has an elongation of *216
inch per unit of its length, a bas^f 10 inches has an elonga-
tion of '42 per unit of its length, or nearly double what it is
in the former case. The relation between the length of the
bar and its maximum elongation per unit, may be approxi-
mately expressed by the following formula, viz. —

/=-18 +

2 5

where L represents the length of the bar, and / the
elongation per unit of length of the bar.

It is difficult to measure accurately the elongations in 2^
inches, but the following Table shows the elongation per
unit of weight and length at various temperatures, as
exhibited in the experiments on rivet iron.

128

TENSILE STRENGTH OF RIVET IRON.

Teinperature,
Fahr.

o
-30

+ 60

114

212

250

270

310

325

415

435

Red heat.

Elongation per ton
per inch.

•00284
•00297
•00197
•00177
•00173
•00142
•00182
-00164
•00192
•00175
•00153
•00175
•00192
•00341

Mean Elongation

per Unit of Length

and Weight.

}

•00284
•00247
•00177
•00162

•00178
•00164
•00183
•00341

These results show that the eloDgation per unit of length
and weight somewhat decreases upwards towards the
temperature of maximum strength, and thence decreases,
so that whilst the elongation is nearly the same at all ordi-
nary temperatures, it is more than doubled at red heat.

129

IV.

ON THE COMPARATIVE VALUE OF VARIOUS KINDS OF
STOKE, AS EXHIBITED BIT THEIR POWERS OF RESIST-
IKO COMPRESSION.

(From the Memoirs of the Manchester Philosophical Societj.)

Our knowledge of the properties of stone, viewed as a
building material, is verj imperfect, and our architects
and stonemasons have yet much to learn concerning the
difference between one kind of stone and another, both as
regards their chemical constitution, their durability, and
their powers of resisting compression. On this subject we
have the experiments of Gauthey, Rondelet, and Bennie,
which to some extent supply the deficiency and furnish
data for the resistance to a crushing force of a consider-
able variety of stone. These are, however, to some
extent inapplicable to the purposes for which such data are
required ; and not finding them in exact accordance with
the results of some experiments recently made, I have
endeavoured to inquire into the causes of the discrepancy,
and to account for the difference.

Stone is found in various forms and conditions, em-
bedded in and stratified under the earth's surface. That
portion of it which is used for building purposes, is a
dense coherent brittle substance, sometimes of a granu-
lated, at others, of a laminated structure. These qualities
varying according to its chemical constitution and the mode
in which it has been deposited. Sometimes the laminated

130 ON THE COMPAI&ATIVE VALUE

and granular rocks alternate with each other ; at others^ a
rock of a mixed form prevails, partaking of the charac-
teristics of both structures. Independent of these pro-
perties is its power of resistance to compression, which
depends chiefly upon its chemical combinations and the
pressure to which it has been subjected whilst under the
earth's surface from the weight of superincumbent
materials. The granite also, and other igneous rocks, owe
their hardness to their having crystallised more or less
rapidly from a fused mass.

In attempting to ascertain the ultimate powers of resist-
ance of rocks which have been deposited by the action of
water, it is necessary to observe the direction in which the
pressure is applied, whether in the line of cleavage, or at
right angles to it. In nearly all of the following experi-
ments this precaution was attended to, and it will be seen
that the strength is far greater when the force is exerted
perpendicularly to the laminated surface, than when it is
applied in the direction of the cleavage. In building with
such stone, it is also important that it should be laid in the
same position as that in which it is found in the quarry, as
the action of rain and frost rapidly splits off the laminae of
the stone when it is placed otherwise. The strength of
the Igneous, or crystalline rocks, is the same in every
direction, owing to the arrangement of the particles of
which they are composed.

It might have been advantageous to have ascertained,
by analysis, the chemical composition of the substances
experimented on ; but as this varies in almost every lo-
cality, and that in accordance with the superincumbent and
surrounding strata, this is of less consequence in practice
than a knowledge of absolute facts in connection with the
properties of the material. Deductions from direct experi-
ment are of no small importance to the architect and
builder, as he should not only be acquainted with the

OP VARIOUS KINDS OF STONE.

131

strengths and other properties of the material on which he
works^ but also with the changes of those qualities under the
varied forms of stratified^ metamorphic^ and igneous rocks.

On the durability of the specimens^ I have made np
further inquiry than in regard to their power of resistance
to strain. Any addition would require a separate investi-
gation into the chemical constituents of the different spe-
cimens, and into those changes to which stone of almost
every description is subjected when exposed to the action
of the atmosphere. In omitting this branch of the in-
vestigation I have not forgotten its importance, but have
very properly left its development to abler hands.

Before giving the results of the inquiry, I may observe
that a portion of the experiments were undertaken at the
request of Mr. E. W. Shaw, the surveyor of the borough
of Bradford, in Yorkshire, in order to ascertain the best
and strongest qualities of stone for paving the streets of
that town. The following Tables give the result of the
experiments on fifteen specimens of Yorkshire sandstone,
and on some specimens from Wales and other places, as
follow : —

Experiments to determine the force necessary to fracture y
and subsequently to crush^ 2-m. cubes of Sandstone from the
Shipley quarries, Bradford. The pressure applied in the
direction of the cleavage.

No. of

Bxperi-

ment.

WeighU
laid on
iulbi.

Remarks.

No. of

Expert.

ment.

WeighU
laid on
in lbs.

Remarks.

Specimen No. 1.
Shipley.

Specimen No. 2,
Heaton.

12
13

• •
16

31,732
33,524

38,900

fractured.

• • •
crushed.

11
12

• •
16

31,732
33,524

40,692

fractured.

• • •

crushed.

K 2

132

ON THE COMPARATIVE VALUE

No. of
Experi-
ment.

Weiishto

l«id on

in lbs.

Remarks.

No. of
Experi-
ment.

Weights
laid on
in lbs.

Remarks.

Specimen No. 3.
Heaton Park.

Specimen No, 4.

8
9

10
11

26,356
28,148
29,940
31,732

fractnred.
crushed.

This specittien was defective
and crushed as the first weight,
28,148 lbs., was laid on.

Specimen No. 9.
Old Whatley.

Specimen No. 10.
Manningham Lane.

11
12
13

31,732
33,524
35,316

fractu*ed and
crashed suddenly.

8
9

• •
14

26,356
28.148

37,108

fractured.

. . •
crushed.

The results of the Experiments 1, 2, 3, 9, 10, fractured
and crushed in the line of cleavage, are given in the fol-
lowing Table,

No. of
Speci-
men,

Locality.

Sixe.

Weight at which
it fractured.

Weight at which
it crushed.

1
2
3
9
10

Shipley, Bradford .
Heaton .
Heaton Park .
Old Whatley.
Manningham Lane

2-in cube.

n
»f
w
»>

33,524
33,524
29,940
35,316
28,148

38,900
40,692
31,732
35,316
37,108

Mean . ...

J 2,090

36,749

OF VARIOUS KINDS OF STONE.

133

Experiments to determine the force required to fracture^
and subsequently to crush, 2-2n, cubes of Sandstone from the
Shipley and other quarries, near Bradford. Pressure being
applied at right angles to the cleavage.

No. of
Experi-
ment.

WeiKhU
laid on
in lbs.

Remarks.

No, of

Expert.

Dient«

Weights
laid o\\
in lbs.

Remarks.

Specimen No. 5.
Idle Quarry,

Specimen No. 6.
Jegrum*s Lane.

15
16
17
18

38,900
40,692
42,484
43,380

fractured,
crushed.

18
19

• •
22

44,276
45,172

4*7,860

fractured.

• • •

crushed.

Specimen No. 7.
Spinkwell.

Specimen No. 8.
Copp7 Quarry.

10
11

• •

29,940
31,732

3*7,1 08

fractttred.

• • •
crushed.

• •
16

• •
18

37,108
39,796
41,588

first fracture,
second fracture,
crushed.

Specimen 1^

0. 11 fa

iled.

Results of Experiments on Specimens 5, 6, 7, 8, fractured
and crushed at right angles to the cleavage.

Naof
Specimen.

Locality.

Sise.

Weight at which
it fractured.

Weight with which
it cruahed.

7
8

Idle Quarry, Brad-
ford
Jegrum*s Lane .
Spinkwell .
Coppy Quarry *

Mean

2-in. cube
»»

•

42,484
45,172
31,732
37,108

43,380
47.860
37,108
41,588

• .

39,124

42,484

K 3

134

ON THE COMPARATIVE VALUiS

By the foregoing experiments it will be observed that
the resisting powers of stone to compression^ are greatest
when the pressure is applied perpendicularly upon the bed
or laminated surface, and that in the ratio of 100: 82 in
the force required to fracture, and 100 : 86 in the force
required to crush this description of stone. Hence, as
already observed, the powers of resistance of every de-
scription of laminated stone, are most effective when the
beds are placed horizontally or perpendicularly to the
direction of the pressure, and this position is the more im-
portant when the stone is exposed to the atmosphere, as it
partially prevents the absorption of moisture, which in
winter tends to destroy the material by the contraction of the
stone and the expansion of the water at low temperatures.

Experiments to determine the force required to fracture
and crush 1-tw., l^-in., and 2-in. cubes of stones from Scot-
land y Wales y and other places.

No. of

Expert.

meut.

Weight

laid on

in lbs.

Remarks.

Ko. of

Expert.

ment.

Weight

laid on

in lbs.

Remarks.

Specimen No. 12. Granwacke.

Fenmaenmawr, Wales.

2-in. cube.

Specimen No. 14. Granite.

Mount Sorrel.

2-in. cube.

• •

29
30
31

40,692

63,988
65,780
67,572

slight fracture,
second fracture,
crushed.

19
20
21
22

46,068
47,860
49,652
51,444

fractured, and af-
ter a slight rest
crushed.

Specimen No. 1 5. Granwacke.

Ingleton.

2-iD. cube.

Specimen No. 16. Granite.
Aberdeen.
2-in cube.

• •

« •

35,316

47,860*

53,236

first fracture,
second fracture,
not crushed.

26,356
27.546

28148
28,340

fractured,
not crushed.

OF YABIOUS KINDS OF STONE.

135

No. Of
Experi-
ment.

Weight
laid on
in lbs.

Remarks.

No. of
Experi-
ment.

Weight
laid on
in lbs.

•

Remarks.

Specimen No. 17. Syenite.

Mount Sorrel.

9-in. cabe.

Specimen No. 18. Qranite.

Bonsw.

l)-in. cube.

17
18
19
20

42,484

44,276
46,068
47»284

cmshed.

2
3

. •
7

15,604
17,396

24,564

fractured in two
nearly equal pts.
cnished.

Specimen No. 19. Furnace Granite.

Inverary.

1^-in. cube.

Specimen Na 20. Granite.

1^-in. cube.

4
5
6

19,188
20,980
22,772
24,564

cnished.

4
5
6

19,188
20,980
22,772
24,564

fractured,
crushed.

Specimen No. 21. Limestone.

1^'in. cube.

Specimen No. 22. Limestone.

1^-in. cube.

1
2
3
4

13.812
15,604
17,396
19,188

•

fractured,
crushed.

2
3

4
5

15,604
17,396
18,292
19,188

ft'actured.
crushed.

Specimen No. 23. Magnesian lamest*

Anston.

1-in. cube.

Specimen No. 24. MagnesianLimest.
Worksop.
1-in. cube.

1
2

« •
10

1258
2154

fractured*

13
14

• •

3,834
3.946

fractured.

3050

crushed.

7,098

crushed.

Specimen No. 25. Sandstone.
1-in. cube.

Specimen No. 26. Sandstone.
2-in. cube.

8
9

• •
13

2938
3050

fractured.

11
12

* .
20

9,770
10,218

12,22V

fractured,
cmshed.

3498

crushed.

K 4

136

ON THE COMPARATIVE TALUE

Results of Experiments on stone from North Wales and
other places. Specimens Nos, 12, 14, 17, 18, 19, 20,21,
22, 23, 24, 25, and 26.

Weight

Pre«sure

No. of
Speci-

Description
of Stone.

Locality.

Sixe.

with
which it

required
to crush a

men.

fractured.

crushed.

2-Jn. cube.

in lbs.

Grauwacke .

Penmaenmawr .

2-in.cube.

40,692

67,672

67,572

Granite.

Mount Sorrel .

51,444

Syenite .

t» *» • •

»»

47,284

Granite. .

Bonaw, Inverarjr

1i-in.cube

17,396

24,564

43,669

Furnace, i, . •

*«

24.564

24,564

43,669

«•

(A)

«>

22,772

24.564

43,669

Limestone .

(B)

17.396

19.188

34,112

(C)

»t

18,'J92

19,188

34,112

•)

Anston ....

1 .in. cube.

2,154

3,050

12.200

««

Worksop ...

»»

3946

7,098

• 28,392

Sandstone .

»>

3,050

3,498

13,992

2in. cube.

10,218

12,228

12.228

The Welsh specimen of grauwacke, from Penmaen-
mawr, exhibits great powers of resistance, nearly double
that of some of the Yorkshire sandstones, and about one-
third in excess of the granites, excepting only the granite
from Mount Sorrel, which is to the Welsh grauwacke, as
•767 : 1. Some others, such as the Ingleton grauwacke,
supported more than the granites, but are deficient when
compared with that from Penmaenmawr. The specimen
No. 23 is the stone of which the Houses of Parliament
are built. Specimens Nos. 26 and 26 were broken to
show experimentally the ratio of the powers of resistance
as the size is changed. The results are suiBciently nearto
prove that the crushing weights are as the areas of the
surface subjected to pressure.

The specific gravity and porosity of the different kinds
of rock vary greatly, and Mr. Shaw, in his desire to
obtain the best quality of Yorkshire paving stone, had
those from the neighbourhood of Bradford carefully tested

OF VABIOD8 KINDS OF STONE.

137

in regard to their powers of absorption ; the experiments^
which were conducted with great precision, gave the
following results.

Experiments to ascertain the amount of Water absorbed by

various kinds of Stone.

Weight

Propor-

No. of

Description
of Stone.

Weight

after im-

Diflfer.

tion

Speci-

TiOcality.

before im-

mersion

ence of

absorbed.

men.

mersion.

for

Weight.

one part

48 hours.

lbs.

Sandstone .

Shipley . « . .

6-4687

6'5546

•0659

63-6

Heaton . . .

5-2578

5-3632

-1064

49*8

Heaton Park

6-1718

6-2896

•1171

441

Spinkwell . .
Idle Quarnr . .
Jrgrum's Lane ,
Spinkwell . .
Coppy Quarnr
OldWhatley

5-2968

6-4726

•1758

30-1

6-7178

6-82r8

-1016

56-3

6-5976

6-7187

•1211

46-2

6-6767

6-7851

•1094

53-8

6-5703

6-6914

'1211

46-0

6-4726

6-6132

•1406

3M-9

Manniugbaxn Lane .

6-4882

8-6093

'1211

46-3

>i If

6-6289

5-7539

•1250

45*0

Grauwacke .
Granite .

Wales ....

6-4101

6-4140

•0039

1641-0

Mount Sorrel . .

6-6875

5-6992

•0117

485-0

'f ff • •

6-8007

5-8124

•0117

40S0

Grauwacke .

Ingleton . . .

5-7500

6-7539

•0039

1»626

From the above Table it will be observed that specimen
No. IS^ the Ingleton grauwacke^ is the least absorbent,
and No. 12^ the Welsh grauwacke, absorbs almost as
little, while Nos. 9 and 14 of the sandstones absorb most.
The granites, though closely granulated, take up much
more water than the grauwackes, but less than the sand-
stones. The resistance of the grauwacke specimens to
the admission of water is four times that of the granite,
and thirty-six times that of sandstone, such as is found in
the Yorkshire quarries.

ON THE COMPARATIVE VALUE

1
»

DtKtlpHoH

Locsllly,

s...

si-
ll

Grapile .

S.Dd««...

HMlon Park*

s;k:.s,'"

Hdudi Soricl
Mounl SomI

Mb.

UBS
1-4 M

■67!

33^M
d'eFa

98,14;

n'.m

W.SM

Ibi.
38,S00

SI,JW
67,6Ta

ItM.

■is

9,sn

3,050

COM

4-833
14-1)40

t-SM
B-n4i

46-S

sa-g

1H-D
1641-0

49V0
19K-6

On comparing the results of the experimenta on the
Yorkahire sandstones, it will be seen that the difference of
resistance to pressure does not arise so much from the
variable character of the stone in different quarries, as
from the position in which it is placed as regards its
laminated surface, the difference being as 10 : 8 in favour
of the etone being crushed upon its bed to the same when
crushed in the line of cleav^e ; the same may be said of
the limestones.

Comparing the strengths indicated with those obtained
by other experiments, I find a very close approximation in
the granites, but considerable difference in the Yorkshire
eandstones. Mr. Bennie obtained his specimens from the

* Presaui-e applied in the direction of the cleavage.

t Frauoie ftpplied perpendicularlj on the bed of the etone.

OF VARIOUS KINDS OF STONE.

139

same district, the valley of the Aire ; but the force re-
quired to crush the Bromley Fall stone was much less
than that required to fracture similar specimens from the
Shipley quarries. The following Table gives some useful
results for comparison.

Crashing Force

OescriptioD of Material.

in lbs. per

Authority.

iquare iach.

Porphyry ....

40,416

Ganthey.

Qranite, Aberdeen .

11,209

Rennie.

„ mean of 3 yarieties .

11,564

Experiments 14, 18, 19.

Sandstone, Yorkshire

6,127

Rennie.

,, mean of 9 yarieties

9,824

Experiments 1 to 9.

Brick, hard ....

1,886

Rennie.

yy red ....

805

Rennie.

From the above it is evident that there is a considerable
difference between the results of Mr. Rennie's experi-
ments and those in the preceding Tables in the case of
the sandstones. This may, perhaps, be due to the different
methods pursued in the experiments, or from taking the
first appearance of fracture as the ultimate power of resist-
ance. Whereas, there is in some cases a difference of nearly
a third between the weight required to produce the first
crack, and that required subsequently to crush the specimen.
* This is the more remarkable as all the specimens did not
appear to follow the same law, as in some the weight which
fractured the specimen by a continuation of the process
ultimately crushed it Experiments of this kind require
close observation, and the reason just given may probably
account for the difference between Mr. Rennie's and my
own results.

All information respecting the strength of materials
must be derived from direct experiment, which is always
the safest and best guide ; and fully aware of the import-
ance of this fact, I have deemed it expedient to append
the following list of the bearing powers of some other

140 ON THE COMPARATIVE VALUE

materials employed in building, and to which reference
may be made in any case where the load is excessive, or
where material is subjected to severe strain.

The necessity of these experiments was the more
apparent some years since, in the construction of the
Britannia and Conway tubular bridges, when fears were
entertained of the security of the masoniy to support,
upon the given area, the immense weight of the tubes,
upwards of 1500 tons, resting on one side of the tower.
To ascertain how far the material (Angleeea limestone)
was calculated to sustain this load, the following experi-
ments were instituted by Mr. Latimer Clarke.

*^ Results of experiments made with actual weight on the
materials used in the Britannia bridge^ January y 1848.

Bbigkwobk.

lbs. per square
inch.

No. 1. — 9-in. cube of cemented brickwork
(Nowell and Co), No. 1 (or best quality)
weighing 54 lbs., set between deal
boards. Crushed with 19 tons 18 cwt.
2 qrs. 22 lbs =551*3

No. 2. — 9-in. cube of brickwork. No. 1 weigh-
ing 53 lbs., set in cement Crushed
with 22 tons 3 cwt. qr. 17 lbs. . . =£:612-7

No. 3. — 9in. cube of brickwork. No. 3 weigh-
ing 52 lbs., set in cement. Crushed
with 16 tons 8 cwt. 2 qrs. 8 lbs. . . =454 '3

No. 4. — 9J-in. brickwork. No. 4 weighing 55^
lbs., set in cement. Crushed with 21
• tons 14 cwt. 1 qr. 17 lbs. . . . =568*5

No. 5. — 9-in. brickwork, No. 4 weighing 54^
lbs., set between boards. Crushed with
15 tons 2 cwt. qr. 12 lbs. . . =417*0

Mean . . . .521*0

OF VABIOUS KINDS OP STONE. 141

Note. — The last three cubes of common brick con-
tinued to support the weight, although cracked in all
directions ; they fell to pieces when the load was removed.
All the brickwork began to show irregular cracks a con-
siderable time before it gave way.

The average weight supported by these bricks was 33*5
tons per square foot^ equal to a column 583*69 feet high^
of such brickwork.

Sandstone.

Ibi. per sqaare
inch.

No. 6. — 3-in. cube red sandstone, weighing 1 lb.
14|^ oz., set between boards (made quite
dry by being kept in an inhabited
room). Crushed with 8 tons 4 cwt. qr.
19 lbs =2043-0

No. 7. — 3-in. cube sandstone, weighing 1 lb. 14
ozs., set in cement (moderately damp).
Crushed with 5 tons 3 cwt. 1 qr. 1 lb. . = 1285'0

No. 8. — 3-in. sandstone, weighing 1 lb. 15 J ozs.,
setin cement (made very wet). Crushed
with 4 tons 7 cwt. qr. 21 lbs. . . = 1085-0

No. 9. — 6-in. cube sandstone, weighing 18 lbs.,
set in cement. Crushed with 63 tons
1 cwt 2 qrs. 6 lbs =3924-8

No. 10. — 9i-in. cube sandstone, weighing hS^
lbs., set in cement (77^ tons were placed
upon this without effect, = 2042 lbs.
per square inch, which was as much as
the machine would carry).

Mean 2185-0

All the sandstones gave way suddenly y and without any
previous cracking or warning. The 3-in. cubes appeared
.of ordinary description ; the 6-in. was fine grained, and

142 ON THE COMPARATIVE VALUE

appeared tough and of superior quality. After fracture
the upper part generally retained the form of an inverted
square pyramid about 2^-in. high and very symmetrical,
the sides bulging away in pieces all round. The average
weight of this material was 130 lbs. 10 ozs. per cube foot,
or 17 feet per ton.

The average weight required to crush this sandstone
is 134 tons per square foot, equal to a column 2351 feet
high of such sandstone.

Limestone.

lbs. per square
inch.

No. 11. -3-in. cube Anglesea limestone, weigh-
ing 2 lbs. 10 ozs., set between boards.
Crushed with 26 tons 11 cwt. 3 qrs.

9 lbs , .=6618-0

This atone formed numerous cracks and
splinters all round, and was considered
crushed ; but on removing the weight
about two-thirds of its area were found
uninjured.

Na 12. — 3-in. limestone, weighing 2 lbs. 9 ozs.,
set between deal boards. Crushed with
32 tons 6 cwt. qr. 1 lb. . . . =8039-0
This stone also began to splinter externally
with 25 tons (or 6220 lbs. per square
inch), but ultimately bprQ as above.

No. 13. -^3- in. limestone, weighing 2 lbs. 9 ozs.,
set in deal boards. Crushed with 30
tons 18 cwt. 3 qrs. 24 lbs. . . . =7702-6

No. 14. — Three separate 1-in. cubes limestone,
weighing 2 lbs. 9 ozs., set in deal boards.
Crushed with 9 tons 7 cwt. 1 qr. 14 lbs. = 6995-3
All crushed simultaneously.

Mean .... 7338-2

OP VARIOUS KINDS OF STONE.

143

All the limestones formed perpendicular cracks and
splinters a long time before thejr crushed.

Weight of the material from above = 165 lbs. 5 ozs.
per cubic foot, or 13 J feet per ton.

The weight required to crush this limestone is 471*15
tons per square foot^ equal to a column 6433 feet high of
such material.

Previously to the experiments just recorded, it was
deemed advisable not to trust to the resisting powers of
the material of which the towers of either bridge were
composed; and, to make security doubly sure, it was
ultimately arranged to rest the tubes upon horizontal and
transverse beams of great strength, and by increasing the
area subject to compression, the splitting or crushing of
the masonry might be prevented. This was done with
great care, and the result is the present stability of those
important structures.

In conclusion, the following general summary of results,
obtained from various materials, shows their respective
powers of resistance to forces tending to crush them.

GENERAL SUMMARY OF RESULTS ON COMPRESSION.

Iron

and

Steel

Description of Material.

Crushing force

in lbs. Authority,

per square inch.

rCast steel . . . r . . .

Blister steel

Fairbalm's Experiments
. , on the Mechanical Pro-

TkiAA •* <iA !*• V *'••»«•... -pertlesof Metals.— Trans-

Ditto (from 12 meltings) . . 163,744 Sujtions of the British

Ditto (from ordinary castings) 89,600'^ Association, 1854.

Cast iron (white, derived from 1 oi ^ oi c \
14 meltings) j ^14,81 6

Stone .

Porphyry

Grauwacke, Penmaenmawr
Granite, mean of 3 . . .
Sandstone, Yorkshire . •
Ditto, mean of 9 exprmts.
Ditto, Runcorn • . . .
Limestone .•...•
-Ditto, Anglesea ....

40,416 Gauthcy.
16,893 Exprmts. No. 12.
11,565 Do. Nos. 14, 18, 19.

6,127 Rennie.

9,824 Exprmts. 1 to 10.

2,185 Clark.

8,525 Exprmts. 21, 22.

7,579 Clark.

144 ON THE COMPABATIVE VALUE OP STONE.

Stone

Description of MateriaL

Ditto, Magnesian — mean .

Brick, hard

Ditto, red

Ditto, mean of 4 exprmts.

fBox

English Oak (dried) . .
Ash (ditto) . .

Plum tree (ditto)

Timber, -j Beech 6,402

Red Deal 5,748

C^dar 5,674

Yellow Pine 5,375

Crushing force

in lbs. Authority.

per square inch.

5,074 Exprmts. 23, 24.

1,888 Bennie.

805 „

1,424 Clark.

9,771
9,-509
9,363
8.241

Hodgkinson.

The above summary gives pretty correct data for the
guidance of the practical builder in the application of
these materials when subjected to a simple crushing force.
The experiments might be greatly extended to stone from
other localities^ but the specimens are of a sufficiently
varied character to aiford the necessary information to
those employed in the constructive arts.

145

PART 11.

LECTURES.

LECTURE L

ON POPULAR EDUCATION.

The object I have in view in this address is to direct
your attention to certain principles which I hold to be
true, and which I consider essential to the development of
the human mind, the formation of character, and the right
exercise of our duties to society. In the investigation of the
all-important question of education, I hope you will give me
your attention whilst I endeavour to lay before you such,
facts as seem to elucidate a subject on which no two men
appear to be agreed, and which has occupied the attention
of the statesman and philanthropist from the earliest period
of our history down to the present time. Notwithstanding
the number of treatises that have been written, and the
number of speeches that have been delivered, we are still
far short of a sound national system of education ; and it
appears questionable, as society is constituted in this
country, whether any system which may be called national
would ever supply the wants of the different classes into
which the population of the kingdom is divided. Many

146 LECTUBE I.

of the difficulties which present themselves would be re-
moved if the different denominations of religionists could
agree upon a sound system of secular education^ supple-
mented by some general principles of faith to which no
real professor of Christianity could object, and on which
to build the great moral structure of liberty, honour, and
independence. There cannot exist a doubt that the safety
and well being, and even the very existence of the state,
depends on the education of the people ; and our intel-
lectual enjoyments are chiefly derived from the instructions
we have received, and the examples which have been set
before us, in early life. How essential is it, therefore,
that these instructions should inculcate not only the lead-
ing truths of natural science, but the great principles of
morality by which our future lives are to be governed,
and on which depends our bearing towards our families
and society at large.

It is not for me to demonstrate what these principles
are ; they vary according to the system of education that
may be practised, and the prejudices which that education
may inculcate. Let us, however, be assured that the
moral world is governed by the same Great Power as the
external creation, from whose determined laws we cannot
deviate without injury and danger to ourselves and others.
If this be the case, the instructions we receive ought to be
such as would teach us to know right from wrong, and how
far, through life, our conduct accords with the principles
under which our education has been conducted. In this
discussion it is not my intention to speak, directly or in-
directly, of religious instruction ; and although I hold that
religious education is essential to the well being of society,
I nevertheless leave all matters of belief to the discretion
of parents, as regards the principles upon which their
children should or should not be educated.

What we have to treat of on this occasion is the charac-

ON POPULAR EDUCATION. 147

ter of training a young man should receive, whose only
inheritance is a sound mind and a strong constitution, in
the various stages of his early life, and how his powera
should be cultivated for his own happiness and the benefit
of those with whom he has to live. Viewing the subject
in this lights it will be necessary to divide it as follows : —

1st. — Elementary Teaching and Physical Training.

It has been rightly observed that a sound foundation is
essential to a secure superstructure ; and this truism applies
as forcibly to the development and cultivation of the
human mind as it does to material constructions.

What should therefore first engage our attention, from
infancy up to five years of age, is to nurse and encourage
the growth of the body, to strengthen the muscles, and
thus to establish a sound foundation for the higher powers
of intellect by ensuring to the recipient a vigorous and hardy
constitution. During this period the mind receives impres-
sions as a child, which in after life will influence its
conduct as a man ; and very much will depend upon the
mother, or those that have the care of infancy, that these
impressions be of the right sort, and that they have a
direct tendency to virtue, and those dispositions of charac-
ter which influence the future fortunes of the man. In this
early stage of what can scarcely be called tuition, but
which nevertheless forms the nucleus of a system, it must
be borne in mind that a healthy body is the twin sister of
a sound mind, and that any neglect or injury to the former
is sure to affect the latter, and weaken the powers we
are anxious to cultivate. In future developments, how
much therefore depends upon the mother, and how very
important it is that we should have good mothers pos-
sessing all the qualifications necessary to bring up their
children^ and prepare them for the reception of those

148 LECTUBE I.

principles we are desirous they should inherit In after life-
This impression suggests the all-important question of the
education of women; and on this point I shall have to
trouble you with a few observations.

I have already stated that our earliest impressions^ whether
for good or evil, are received from the mother. Almost
every child is endowed with amazingly quick powers of
imitation ; it is moulded and impressed by its earliest
associates, and when the influence and example of a
prudent and discreet mother predominates, the fruits of
a sound judgment and a well spent life are almost sure to
be forthcoming and ripened to maturity. Hence it be-
comes a question of deep interest to the well being of
society that the first step in our educational career should
be applied to the softer sex, in order that our minds may
derive from that source the germs of correct mental cul-
ture and desires that tend upwards to honour and to
virtue. Much may be said in illustration of the educa-
tion of females ; but the subject is one of difficulty, and
requires the most careful consideration, in devising a
system which shall harmonise with the feelings of the sex,
while it strengthens the understanding and cultivates the
aifections of the heart.

It has been stated that the female mind Is not equal to,
and cannot realise, the sterner duties of the male. This
appears to be a mistake, as we find that the minds of
women are not only susceptible of large development, but
for penetration, quickness of perception, and high attain-
ments in mental culture, they are fully equal, if not
superior, in some cases, to the active and more rigid
characteristics of the other sex. These qualifications
stand prominently forward in the acquirements of the
female writers of the present day ; and to the credit of the
sex we may instance as examples the works of Mrs. Somer-
ville in science, and those of Miss Evans, Mrs. GaskeU

ON POPULAR EDUCATION. 149

and others in the leading walks of fiction and polite
literature.

Again^ we find in the female mind a degree of aptitude
and fineness of touch in works of precision, that we almost
look for in vain in the labours of man. The patient sub-
mission to daily toil, the untiring energy, and minute
accuracy of the seamstress is proverbial, and in all the
lighter descriptions of labour, such as watchmaking,
sewing, weaving, &c., women are found to be better
qualified than men. In commercial transactions the same
steadiness of action, patient endurance, critical attention
to minutidB, is observable in women ; and the duties of the
bureau, counter, and book-keeping are performed by
women with a degree of exactitude in France that is
enough to put their partners in life to the blush. All
these duties are done by women, and they are well done,
during a period in some cases when their husbands and
sons are in the cafe or at the billiard-table.

But of all other occupations, woman is seen to most ad-
vantage in the domestic circle — in the management of her
home and the education of her children. It is here where
the mother becomes the instructress, the example, and the
glory of her family ; and it is to these duties, be she rich
or poor, that the affections of the heart should be
moulded, and the faculties of the mind should be trained.
This species of culture should form a part of our national
system, and the education of the sex should never be left
to chance, but they should be taught from early life the
value of time in the efficient and honest discharge of
their domestic duties.

Much has yet to be accomplished in this direction
before we can calculate upon raising up for the service of
man a phalanx of good and virtuous mothers, endowed
with all the finer feelings of their nature, united to a large
stock of sound common sense,

L 3

160 LECTURE I.

2nd.— /V(wn the Age of Five to Ten Years.

At this age we may safely commence a system of pre-
paratory instruction in reading, writing, and arithmetic ;
and supposing the child endowed with a healthy frame and
clear intellect, he will, in the course of that time, have
mastered the ordinary rules of arithmetic and have ac-
quired a taste for reading. In this stage of progress I
would observe that much wUl depend upon the books
selected for instruction. In my opinion they should
amuse as well as instruct ; and those containing stories of
animals and narratives of individuals will be the most
acceptable and attractive to the growing intellect of the
child. Tales and descriptions of this kind will give him
a taste for books, and a pleasure in their perusal, which he
will not lose in riper years. It is astonishing what may
be done with children at a tender age. Their powers of
imitation, love of play, and all the endearments of life, are
in a high degree attractive ; and much will depend upon
the parents, the mother in particular, as to the class of
instruction that should be followed, whether on the do-
mestic hearth or at school. I am glad to observe that
the system of tuition is greatly improved since my time»
and that the school books of the present day are more
attractive and better adapted to the capacity of the child
than at any previous epoch in the history of our edu-
cational system. From fifty to sixty years ago, Barrow's
Collection, the Bible, and Dilworth's Arithmetic, were
the only books in use, and in case of any dulness oi^
want of comprehension, the boy's intellects were enlivened
by an application of the most sensitive description, so
much so in fact as to bring tears into his eyes. Thid
Was a general practice in those days, and I well remem-
ber what was called the clearing day, which took place
every Thursday, when our accounts were settled for the

ON POPULAR EDUCATION, 151

week, by the mistaten idea of attempting to force in at
the extremities what was unable to penetrate into the
more noble and more intellectual part of the system. It
is fortunate for the present generation that a more merci-
ful system of management has been introduced, and that
the schools of the present day are much better adapted
for the cultivation of the minds of youth than at any
former period when measures of much greater severity
were adopted. It will not be necessary to enlarge upon
this division of the subject farther than to observe that
at this tender age it is essential to the fature happi-
ness of the child, and his usefulness in after life, that he
should be kindly treated, and that upon a system calcu-
lated to develope his latent powers, and prepare him for a
higher and more extended sphere of instruction. These
are my views in regard to the early stages of train*
ing ; and although there is a difference of opinion as to
where and in what manner it should be given, I am
nevertheless convinced that it should be received at a
public school.

3rd. — Education during the Period intervening between the

Age of Ten and Fourteen.

Assuming our views of infant education to be correct,
we are now arrived at that stage of probationary exist-
ence, when the boy begins to think something of himself,
and with feelings which deepen into manly independence
he discovers a power which he considers peculiarly his
own, and which he is unwilling to trust in the hands of
others. This feeling should never be suppressed, but
carefully watched and modified in cases where it tends to
encroach upon the rights of others. In a public school it
generally brings its own corrective; and in this little
republic there are those both able and willing to control
the turbulent and self-willed intruder. To the agricultural

152 LECTURE I.

labourer^ the mechanic, and the artisan, this is a time of
vital importance, as at this period may be laid the foimda-
tions of future comfort, success," and renown. I do not
mean by these observations to say that every candidate
for honours in his particular walk of life will succeed ; on
the contrary it id only a few amongst the many that attain
distinction. Yet the prize is worth looking after; but
unless the taste for knowledge, and the power to apply it
be there, it is vain to think of ascending the scale in the
great contests of human existence. I speak from experi-
ence of these matters ; and I can assure you it is a long
time since I discovered that nothing valuable was to be
attained without study, in the first instance, and constant
labour and application in the second. It is, therefore,
important that the boy should never lose sight of the
object he is striving to attain, and that his mind should be
directed to those points of study that are likely to stimu-
late him to action in the full and faithful discharge of his
duties in after life. At this period, whilst the mind of the
pupil is receiving the rudiments of a plain but useful edu-
cation, care should be taken to ascertain the peculiar bent
of his mind, and to encourage tuition in those branches
best suited to his taste, and best adapted to the circum-
stances of his future entrance into life. This is the
suitable time to give instruction in grammar^ history,
biography, arithmetic, geometry, and practical mathe-
matics. All these may be taught with advantage, leaving
subsequently to the pupil himself the choice of a profes-
sion or trade, in which the knowledge he has acquired
can be usefully and properly applied.

Towards the end of his educational course the boy, if he be
aspiring, assumes something of the character of the man. He
begins to assert the dignity of his nature, and looks out for
that description of employment by which he can maintain
himself. This love of labour in early life is characteristic of

ON POPULAR EDUCATION. 153

the youth of this kingdom. And here I cannot do better
than reiterate a part of the speech of the Kight Honour-
able Sotheron Estcourt, the chairman of the Poor Law
Boards who, in his address to the members of the Hants and
Wilts Adult Society, speaking of the difficulty of attach-
ing young persons to educational pursuits, he said that,
*^ in his desire to remedy certain evils, he was persuaded
that anything like an attempt to catch hold of young men
and young women after they leave school, and by holding
out either a pecuniary reward, or in any other nianner
attempting to persuade them to take a deeper interest in
the subject of education than their own minds naturally
induce them to take, will end in failure." And in con-
firmation of the truth of these observations he further
observes, " that it is rather too much to expect that an
employer will consent to keep a boy at school when he
ought to be at work ; and, indeed, even in that case he
doubted whether such a plan would be successful. He
could give an instance in which it was not Some years
ago he was very desirous of doing something of the kind
in his own parish, and engaged two boys to do a certain
amount of work ; but he made an engagement with them
that he would not pay them unless the boy who was not
employed in labour attended the school. He, however,
totally failed, for the boys preferred labour to school, and
both of them left his employment as soon as they could
find others to give it them. He attempted to interfere
artificially with their natural desire, and deservedly
failed." Nothing can be more true than the above obser-
vations ; and the question is, how to deal with this innate
preference for labour so as to make it productive of good
to the individual and beneficial to the community. In the
solution of this question I hope to show that much may
be accomplished in the next division of my subject, viz. —

154 LECTURE I.

4th. — Adult Education from the Age of Fourteen to

Twenty,

This stage of intellectual culture is probably the most
important in the whole scale of mental progress. At this
time the wild passions of youth have to be controlled and
brought within the bounds of moderation^ and at this
period scholastic instruction ends^ and self-culture begins.
This is a period of vital moment to youths when a life of
labour should be relieved by study, having for its object
the acquisition of knowledge based on professional pur-
suits, and calculated to enlarge the faculties of the mind. It
is astonishing how much a young man may gain in this way
without the guidance or assistance of any teacher what-
ever. I will give you an instance from my own ex-
perience. I had to teach myself, and that without the aid
of either tutors or mechanics' institutes, by a course of
reading and practical mathematics, which I pursued from
sixteen to twenty-four with unrelaxed avidity after the
labours of the day were over, and which not unfrequently
encroached upon the hours of sleep. I subjected myself to
this system of self-teaching for five days in the week,
devoting the remainder to pleasure and amusement ; and
now at this advanced period of life I find myself nothing
the worse, but all the better for it I will not trouble you
with further examples, but proceed to state what course
I consider necessary to be pursued in aiding the progress
of a youth in mental culture during this early period of his
career. We ought, in my opinion, to afford a knowledge
of natural science in connection with labour and the profes^
sional pursuits in which those we teach are engaged. A
youth may be a mechanic, an artisan, or an agricultural
labourer, or he may be a soldier or a sailor; it'is all the
same, whatever his professional pursuits may-be> they in-
volve certain duties, and these cannot be property executed

ON POPULAR EDUCATION. 155

■without a knowledge of the laws upon which they are
founded. To become an expert workman in any handi-
craft employment is not entirely the work of the hand ;
on the contrary, the head is the director of every move-
ment, and to effect these skilfally he must possess a know-
ledge of the laws which the Almighty has so intelligibly
and so beautifully written upon the page of nature. A
labourer in the field cannot cut a drain or turn up the soil
by the spade or the plough without having some percep-
tion of the objects of his toil. An artisan cannot weave a
piece of cloth, nor a mechanic execute a piece of ma-
chinery, without some consideration of the principles on
which these operations are conducted, or what I call the
physical truths of construction, applicable in every case as
fixed laws to the operations of man. Nor can a soldier or
sailor, in the defence of his country, adequately exercise
the functions of his profession without some perception of
the great laws by which the arts of attack and defence
are governed. It is in the knowledge of these physical
truths that we shall exercise our varied pursuits with most
benefit to ourselves and most advantage to the community ;
and these should therefore form a part of every man and
every woman's education. Yet in recommending the study
of natural laws bearing upon the duties of life, it is not my
intention, nor is it my desire, to institute a nation of phi-
losophers, but only to instruct the rising generation of
men and women in the more efficient discharge of their
respective duties, and more particularly with a clearer
apprehension of the unerring laws by which every opera-
tion of the human mind is governed, whether in the phy-
sical or the moral world. The economy of nature should
therefore form a part of every man's instruction ; and we
shall best discharge our duty to the - rising generation
by imparting to our successors that knowledge wbioH
leads to nature and to nature's laws.

156 LECTURE !•

In the preceding remarks I have endeavoured to trace
the culture essential to the development of character from
childhood to the age of puberty, in the case of a young man
whose parents are poor, and who is entirely dependent for
subsistence on his own talents and self-reliance. A young
man so placed is in a position calculated to awaken within
him resources which in more favourable circumstances
might have lain dormant. He might, in affluence, go
through life in a quiet unostentatious manner, highly
respectable, no doubt, but wonderfully deficient in energy
compared with those whose characters are marked by their
labours, enterprise, and contributions to the general stock
of knowledge. In fact such a man, beginning the world
with self-reliance alone, is in a condition, independently of
other circumstances, to work out his own fortune with a
certainty that we seldom meet with in those more favour-
ably placed.

Poor Richard, in his almanac, says that ** God helps
those who help themselves ;" and, bearing this truism in
view, a man has nothing to lose, but everything to gain,
by a life of laborious and active industry. Where his
inclinations and habits tend in that direction, he is sure
of encouragement and assistance, and there is no difficulty
in finding those who are both able and willing to lend a
helping hand to one whose mind is imbued with an honest
ambition. To one of well regulated mind there is no plea-
sure so great as to witness the persevering energies of youth
labouring against difficulties in the pursuit of knowledge.
On such occasions most men are ready to encourage the
development of an intellect on which the future career of
the man is already forcibly and strongly marked.

Let us follow historically the leading events of the life of
such a man, — a man who has risen by the force of his own
f alents to distinction, and has been appreciated as a benefac*
tor of his species. W^. have many men of this kind^ for it

ON POPULAE EDUCATION. 151

18 only under a free government, where the necessary facili-
ties for progress are at hand, that such men can flourish.
We may rest assured that such a position has not been
attained merely by aspiration; on the contrary, nothing
valuable is obtained without exertion, and to ensure success
there is nothing for it but indomitable and never-relaxed
perseverance. If you accompany such men as Ferguson,
Franklin, Watt, or Stephenson, in their intellectual pro-
gress, you will be at no loss to discover the secret by which
they attained to greatness. They also had to contend with
difficulties in early life, but a laudable ambition and an
untiring perseverance overcame every obstacle, and their
victories over their early impediments were the harbingers
of their ultimate triumphs.

To rise in the world three qualifications are necessary :
truthfulness, a sound judgment, and persevering industry*

I am of opinion that no man can permanently advance
himself without strict honesty of purpose and adherence to
the principles of truth ; then in the exercise of our pro-
fessional, as well as of our domestic duties, a clear percep-
tion and a sound judgment are necessary to guide us in the
right direction; and, lastly, an unwearied perseverance,
superadded to these qualifications, seldom fails to ensure
to its possessor certain success.

Some may think they have no chance, that no opportu*
nity of distinguishing themselves offers itself ; but this I do
not believe. I can more readily conceive that they have
not sought an opportunity, nor availed themselves of it
when fortune has thrown it in their way. It is of no
use standing and calling upon Jupiter for help, when we
should energetically and at once put our own shoulder to
the wheel. To improve our condition in life we must seize
opportunities as 4hey occur, and to do this we must have
prepared ourselves by the faithful and honest discharge of
our ordinary duties.

158 LECTURE I.

In the early stages of a man's life — I am speaking now
of a working man, who has everything to gain and nothing
to lose — it is necessary that he should carry on his educa-
tion along with his trade ; and I would recommend him,
without a tutor, whom I assume he would be unable to pay
for, to persevere in a course of instructive reading in con-
nection with the trade he has to follow, and one calculated
to make him an expert workman and a useful member
of society. In recommending these studies, I am not one
of those who would impose a rigid observance of duties,
which, to be profitable, must be agreeable, but perse-
verance for a time, until the requisite elementary know-
ledge has been attained, will make further study attractive.
Young people require relaxation, and he would be a hard
preceptor indeed who would deny to them the enjoyments
suitable to their age, as friendships and associations formed
in early life give to later years their happiest and most at-
tractive reminiscences ; and I hope the good sense of the
people of this country will always preserve them from in-
fluences inimical to the innocent amusement of their leisure
hours. The excesses of pleasurable enjoyment must, how-
ever, be guarded against, and on every occasion made sub-
servient to the duties of life.

Let me draw your attention to the position of a young
man of fifteen or sixteen years of .age, thrown on the
world with no other means of subsistence than a robust
constitution, an active mind, and the rudiments of a plain
education, such as reading, writing, and some knowledge
of arithmetic. Let us suppose the means of learning some
handicraft trade within his reach, and that he thus obtains
some small weekly wages sufficient for his maintenance.
Thus placed, with an active mind, a stout heart, and an in-
domitable perseverance, he begins life ^ith many advan-
tages; the necessities of his position will call forth energies
unknown to him before, or to those better provided for, and

ON POPULAE EDUCATION, 159

the pleasure of overcoming difficulties is an encouragement
to action, and renders sensible those qualities of charac-
ter which otherwise might have remained latent. These
are positive advantages, and many a young aspirant who
laments his misfortunes in being thus left to his own
resources, sees only the dark side of the present, whilst the
future is looming in the distance with a flood of light.
Is not then the prize of distinction worth contending for?
Is it not a question for every young man in the circum-
stances I have described to consider whether he will
undertake the task, and not only commence, but pursue, a
course of study calculated to win for him a more honour-
able station in life?

At a time when both mind and hand are under training,
it is desirable that the self-teaching student should pursue
his studies methodically, and not waste his time in vacil-
lation. He must bear in mind that time is the ever-
flowing stream on which he floats to the scene of his
future labours. He must, as the Scotch say, ** put a
stout heart to a stay brae," and never lose sight of the
object he wishes to attain ; he will then make provision for
leisure hours by a course of arithmetic, geometry, and
mathematics, and an equally useful course of chemistry
and physics; and for general reading he could not do
better than study some of our best authors, such as
Addison, Hume, and Goldsmith of the last century, and
Scott, Prescott, and Macaulay of this. In addition, he
may enrich his mind with some of our best poets, begin-
ning with Shakspeare, Burns, and Byron, Southey, Scott,
and Tennyson. All these may be read with advantage,
and interspersed with the newspapers and periodicals of
the day, will lay the foundations of future usefulness in
the more active scenes of life.

Having thus carried the young aspirant over a period
which may last from fifteen to one-and-twenty, he then

160 LECTURE !•

presents himself to the world with a trade in his hand and
a mind fully prepared to act an Important part in life.
Such a person will not be long without employment, and
his previous discipline will have fitted him for the tasks he
has to perform. He respects his employer, and endeavours
to discharge his duty with honesty and alacrity ; in a few
C years he gains his master's confidence, becomes his as-

^N^ sistanVgrobabljI^arries his daughter/ and settles down as
the fatEer of a family and a respectable tradesman for the
remainder of his days. In such a career there is honour
and comfort, and provided his mind is not poisoned and
his independence destroyed by unions and trade clubs, he
may calculate on a prosperous life and a respected old age.
A settlement by marriage with encouraging prospects
does not close a man's education : thai indeed he does not
finish till he dies. We are all scholars and always at school
from infancy to the decrepitude of old age. But a settle-
ment in life is doubtless the beginning of a new era, an-
other stage in our preliminary journey, and along with it
come numerous and important duties, which it is expected
we shall duly and honestly fulfil. Every new phase in our
existence brings new responsibilities, and entails a constant
and growing necessity for extended knowledge ; and pro-
vided we are desirous of making ourselves useful in our day
and generation, we must labour first in the acquisition of
knowledge, secondly in its application, and lastly, we must
constantly strive to attain a life of spotless integrity.

In conclusion, I have to observe that we have much to
be grateful for in the many excellent educational insti-
tutions of which this country at the present time can
boast, and the great facilities now afforded to all in the
attainment of knowledge at the merest modicum of cost.
Compare the present with the times I have alluded to,
and you will find that your fathers had not the advantages
you possess. In my own time there were no mechanics'

ON POPULAR EDUCATION. 161

institutes^ no cheap publications^ no free libraries^ and
comparatively little encouragement given to education.
In those days we had to. borrow books from those who
would lend them^ and he was a happy youth indeed who
found amongst his father's friends and acquaintances one
who would encourage and support him in the pursuit of
knowledge. Learning was then considered a dangerous
thing, and many went so far as to say that education
would be the ruin of the poor and the annoyance of the
rich^ making them discontented with their lot in life, and
paving the way to rebellion and insurrection. Now we
have lived to see the falsity of this doctrine, and I trust
we may yet live to see the labouring man combine with
his daily pursuits the blessings of a mind free from preju-
dice, but full in the enjoyment of intellectual culture.

162

LECTURE n.

ON THE MACHINERY EMPLOYED IN AGRICULTUEE.

Reseabch into the annals of antiquity throws but a
feeble light upon the methods adopted by primitive nations
in the tillage of the soil; or upon the implements em-
ployed in procuring the products of agriculture and con-
verting them into food. The earliest accounts upon which
reliance can be placed are those in the sacred Scriptures,
whence we learn that the Babylonians and Egyptians
were rich in agricultural resources, and that the labours
of the husbandman on the banks of the Nile and the
Euphrates were rewarded by returns of " sixty, seventy,
and one hundred-fold." This large return was, doubtless,
the result, partly of the fertility of the soil, which re-
ceived year by year, on the overflowing of the rivers, de-
posits which enriched the soil; and partly also of the
favouring influence of an almost tropical climate.

It is a mistake to suppose that the farmers of these
remote times were unacquainted with the simpler imple-
ments of agriculture, for even at the present day there
remain enduring records of such instruments in the paintings
on the walls of Egyptian temples, and on the sculptures and
coins of later date. Most of our agricultural implements
may be traced back to an ancient origin, and it is more
than probable that the Egyptian farmer of nearly 3000
years ago had many of the conveniences of the dwelling-
house and well stocked farm-yard that may be seen in our
own homesteads at the present day. Such facts as these

ANCIENT AGRICULTUHE. 163

should make us cautious in assuming to ourselves the
merit of original invention and improvement, when his-
tory furnishes such unmistakeable records of the great
antiquity of machines of similar descriptions.

To another very ancient race, the Egyptians and
Komans, as well as ourselves, were probably indebted for
the discovery and application of many of the machines by
which we cultivate the soil. The very people with whom
we are now prosecuting a deadly feud* are the descendants
of that race to whom we owe some of the most important
aids in the cultivation of the soil, and judging from the
traditionary annals of the country we may conclude that
the inhabitants of Hindostan and Central India were
amongst the earliest to* improve the art of tillage, and to
introduce that system of rotation, by which the soil is
enabled to produce larger and more abundant crops.

Like most other nations the Greeks were at first rather
a pastoral than an agricultural people, and although Hesiod
and succeeding writers have left records upon the subject,
we are less acquainted with the progress and extent of
agriculture in Greece than in Italy, or almost any other
country.

Amongst the Bomans agriculture was regarded as one
of the most important and profitable pursuits, and during
the earlier days of the republic it engaged the attention
of the bravest citizens and most skilful generals. And,
no doubt, in Italy agriculture owed much of its successful
progress to the energies developed and disciplined in the
sterner school of war. The Romans were well acquainted
with irrigation, manuring, ploughing, draining, and other
more obvious processes connected with the fertilisation of
the land and securing its products.

* Written immediately after the revolt of the native army in our Indian
possessions in 1858.

H 2

164 PERUVIAN AaRICULTURE.

During the middle ages agriculture^ no longer consi-
dered an honourable occupation^ sunk in most countries to
the lowest possible condition. The processes of irriga-
tion and manuring were neglected^ or lost^ and hence it
is not surprising that under such a system the products
should not be much more^ according to Humboldt^ than
four times the quantity of the seed sown.

In America^ during the paternal reigns of the Incas of
Peru, agriculture was carried on with great success by
that ancient and intelligent people ; and until overrun by
the Spaniards under Pizarro they maintained their cha-
racter as a civilised community, subsisting on the products
of the soil, which they cultivated upon principles superior
to those known in Europe at the time, and in other re-
spects conducive to the interests and well being of the
people. The Peruvians were well acquainted with the
value of guano^ which, according to Prescott, was pro-
cured from the coast, and was held in such high estima-
tion that no person was permitted, under risk of severe
penalties, to disturb the penguins on the islands during
the time of breeding. Again, their system of irrigation
was upon a magnificent scale, the water being carried
across valleys and rolind the sides of mountains to an
extent far exceeding works of a similar nature in modem
times. All the lessons to be derived from these under-
takings were lost upon the Spaniards, by whom the Peru-
vians and their works were alike neglected and destroyed.

In this country the cultivation of the soil was little
studied as ' a profession, and very imperfectly practised up
to the middle of the last century. Up to the union of
the kingdoms of England and Scotland the crops of corn
are very small in comparison to what they are at present ;
and wheat must have borne a small proportion to the
inferior descriptions of grain, such as oats and rye, with
probably some occasional patches of beans and barley^

YOUNG AND BAKEWELL. 165

Potatoes, carrots, turnips, &c., were unknown, and It is re-
corded that during the reign of Henry VIIL, if a salad was
wanted, messengers had to be sent to Holland and Flanders
for it. Contrasting the mode of living in those days with
the abundant luxuries which are now within our reach,
and the comparison is Immeasurably in favour of the times
in which we live.

From the commencement of the last century to the
year 1760, agriculture gave little or no indication of pro-
gress, and it was not till that time that a movement took
place either in the culture of the soil or the management
of live stock. From that period, however, may be dated
the first step towards a system which has brought the
greater portion of the surface of these islands into cultiva-
tion for the sustenance of our growing and greatly in-
creasing population.

It is to the southern and eastern parts of Scotland, and
to a few distinguished men of the southern part of the
United Kingdom, that we are indebted for these early
movements ; and it is no insignificant compliment to our
countrymen to say that they were the great pioneers in
the improvement of agriculture. Among the earliest and
most distinguished of these we must not forget the name
of Arthur Young ^ the father of English farming, and one
of the most sagacious and talented of men. As a contem-
porary and colleague he allied himself with the eccentric
but gifted Robert Bakewell, the founder of the breed of
Leicester sheep, and the yeoman- farmer and systematic
breeder of live stock. Bakewell was the very ideal of an
independent English farmer ; his house was his castle, and
he used to sit under a huge chimney, clad in a brown coat,
scarlet waistcoat, leather breeches, and top boots. There
he sat, the model of independence, the head of his family,
and lord of his domain. He breakfasted at eight, dined
flt one, supped at nine, and whoever was there, though at

H 3

166 AQBICULTUBAL IMPLEMENTS.

times he entertained princes and royal dukes^ he knocked
out the ashes of his last pipe and to bed at eleven. I
mention these things as instancing the native vigour and
independence of a real English farmer, and I recommend
him to you as a model worthy of imitation.

Our progress since the times of Bakewell has been
rapid and steady, and has placed us in the first position
as agriculturists among the nations of the world. A dis-
tinguished writer on the progress of agriculture says that,
'^ two years ago, a few Englishmen accepted an invitation
of the French government to exhibit in competition with
the picked agricultural and mechanical skill of continental
Europe, and found themselves," as he truly observes, " by
a long interval, first in the arts and sciences required for
producing meat and com in the most economical manner
under a climate not eminently favourable, and on land
which has lost its virgin fertility." He further observes
that, ** the live stock of the British Islands are distin-
guished for three merits, — the early period at which they
become ripe for the butcher ; the great amount of food
they produce in return for the food they consume ; and
the large proportion of prime meat that they yield."

The machinery and implements employed in ayriculture,
to which it is my immediate object to direct your atten-*
tion, are thus spoken of by the same writer : — " The im-
plements of England are distinguished for solidity of con-
struction, simplicity of details, and economy in price, as
well as for the rapidity and completeness with which they
execute their work." Now in this eulogium on English
skill, I think we are all agreed, and ^o far as I can judge
from a careful inspection of the different implements, we
shall have to trace our errors and defects in tillage not to
them, but to ignorance, indolence^ or, what is too often the
case, want of capital on the part of the farmer to ensure
their application*

THE PLOUGH. 167

Three conditions appear to me to be requisite to ensure
complete success, in the cultivation of the soil^ assuming
that the requisite capital is forthcoming to stock and work
the farm.

1st. A never tiring industry^ and an indomitable perse-
verance m farming pursuits.

2nd. A practical knowledge of the chemistry of agri-
culture as regards manures^ composts, the nature of the
soil and substrata, and the treatment to be pursued in ro-
tations to secure an increased fertility*

Lastly, the application of machinery, calculated to work
the farm in the best manner and at the least possible cost.

In making these statements I am probably treading on
dangerous ground, and you will naturally question my
authority in presuming to lecture you in this manner. It
is true that I am not 2l farmery but I have arrived at these
conclusions from a long experience of the benefits derived
from the application of science and the introduction of
machinery in other professions ; and if I have ventured on
this occasion to step out of the way for a purpose in which
I hope to make myself useful, I trust you will take the
will for the deed, and bear with me while I endeavour to
describe objects with which I am more familiar.

The early tools of the husbandman were probably of
the rudest and most simple description, and the first which
would naturally suggest itself to our forefathers in the dawn
of civilisation, would be the branch of a tree which might
answer the part of a spade or a hoe for loosening the soil.
After an instrument so primitive and simple would follow
an attempt at the plough, formed of the crooked branch
of a tree, as in the annexed sketch, and drawn by men or
oxen through the soil. In fact, some ploughs employed at
the present day, in some remote districts of the continent
of Europe, are of the same primitive description, simply
consisting of a block of wood as a handle, without a

M 4

168 AGBICULTUBAL IMPLEMENTS.

coulter^ and with a wooden share, sometimes shod with
iron and sometimes not. Another step in advance would
be when an iron share and coulter were added to an instru-
ment of such primitive construction.

Fig. 27.

Ploughs composed entirely of wood, excepting only the
coulter, share, and a few strips of iron on the mould-
board, were in universal use up to th« middle of last cen-
tury. Since then iron has supplanted the wood, and now
is in most cases the only material employed in its construc-
tion ; and we are mainly indebted to the Scotch for the
introduction of this material in the manufacture of this
important implement.

One of the best and lightest instruments of this kind is
the Scotch swing plough, which is frequently under 2 cwt.,
or about 210 lbs. in weight, and is worked by two horses.
The Lanarkshire plough is different from the above,
making a trapezoidal instead of a rectangular furrow, but
in other respects they are nearly the same in form and
character.

In England most of the ploughs are made with wheels
in front, and are drawn by two or sometimes three horses.
This system requires an additional driver, and it is very
questionable if the work is so well done as by a good

INTRODUCTION OF STEAM. 169

ploughman and pair of horses with the Scotch form of
plough. Such, however, is the force of habit and the
attachment to old tools and old customs, as to encourage
the prejudice against any innovation on the slowly declin-
ing methods of ages that are past. Be this as it may, it
is quite clear that the introduction of the improved iron
plough, which lik« the Minie rifle in the army has super-
seded the clumsy brown Bess of agriculture formerly in
use, and has been to the farmer a most important and
advantageous change.

Other machines of which I wish to treat are so numerous
and important that I shall have to pass over many essential
to high cultivation. Good implements are the twin-sisters of
good cultivation, and the latter cannot be secured without
the former. Such implements are harrows, cultivators to
stir up and loosen the soil, grubbers to gather weeds, drills,
distributors, clod-crushers, and rollers. All these machines
should be part of the farmer's stock, and cannot be dis-
pensed with. It is absolutely necessary in the present
improved state of our knowledge, and with our present
demand for agricultural produce, that a well conducted
farm should have all the machinery necessary to carry out
the new system of management, and so save time and
labour in all the varying operations of husbandry. The
description of all these implements, however, I must leave
to abler hands than my own, and refer you to Stephens'
Booh of the Famiy and similar agricultural writings, where
you have the recommendations of practical farmers, and of
men of high standing and authority in their profession.

To every intelligent observer interested in the progress of
agriculture, it must however appear evident that we are at
the present time in a state of transition, and that the epoch
is fast approaching when a total change is likely to be
effected in the cultivation of the soil ; steam, the great
innovator, having effected revolutions in almost every

170 AGRICULTURAL IMPLEMENTS.

branch of human industry^ is now invading with irresistible
force the province of agriculture. The farmer may object
to and oppose the change^ but he cannot prevent it^ and he
must, in my opinion, ultimately succumb to the necessities
of an increasing population and the onward progress of the
arts.

The first step in preparing the land for the reception of
the seed is the disintegration of the soil, or the loosening
and turning over of the mould to a depth sufficient to
admit the air and to allow the roots of the plant to pene-
trate, in order to ensure its necessary support and supply
of food. To attain these objects, it is found from long
practice to be absolutely necessary to carry off by an
effective system of drainage the superfluous water, and by
these means to allow the rain to percolate through the
soil, the surplus being passed into the drain and only the
requisite quantity of water retained for vegetation. The
number and direction of the drains must be left to the
farmer, who will be guided by the nature of the subsoil
and the position of the field to be drained. The depth to
which the drains should be cut is also a consideration of some
importance. Mr. Smith of Deanston recommended 2 feet 6
inches to 3 feet as the proper depth, but it has since been
found necessary to go as deep as 3 feet 6 inches or 4 feet in
order to protect them from injury and increase the easy flow
of water to the outlets. To accomplish this increase of depth
in the soil the subsoil plough was invented, and we are
indebted to Mr. Smith of Deanston for the introduction of
this very valuable and important implement. It is used
in almost every description of ground that admits of sub-
soiling, and in some cases, when the bottom is a stiff clay,
four or six horses are required to loosen the subsoil, and
ultimately to convert it into a fertile and productive
mould.

Some improvements have been made on this plough.

INTRODUCTION OP STEAM. 171

but the principle on which It was first constructed has not
been altered since its introduction.

To return from this digression on draining to the em-
ployment of steam. It will be in the recollection of every
one present that less than a century ago the machinery for
spinning flax and cotton was confined to a dngle wheel and
spindle, and the produce was limited to what could be
effected with such an instrument by the human hand.
Now the number of spindles employed are counted by
hundreds of thousands instead of by thousands as then»
and instead of working one spindle apiece, one person
now works a thousand. A change of similar character
and extent may yet be in store for the farmer; he would
be a bold man who in these days of change and progress
would stand forward and say that we had arrived in any
art at the final stage of human improvement, the ultimate
goal of human progress. My opinion is that in agriculture
especially, so far from being perfect, we are in a state of
transition, and that it only requires the willing co-opera-
tion of the agriculturist and engineer to establish a new
era in the history of the machinery of agriculture.

Let us, for example, look for a moment at what has
been done and is doing towards the introduction of the
steam plough. Steam power having already been applied
to the miUwork of the farm in threshing, grinding, slicing,
chopping and cutting, it is not unreasonable to suppose
that the same application may be made in the field in the
more laborious operation of breaking up the soil and pre-
paring it for the reception of the seed. Mr. Hoskyns, in
his admirable treatise on the clay farm, states that pre-
paratory tillage consists in the comminution, aeration, and
inversion of the soil, all of which he considers proper to
effect by a properly formed machine at a single operation,
and he is of opinion that, that machine should be a ^^ r«-
volving cultivator^* It is difficulty however^ in the present

172 AGRICULTURAL IMPLEMENTS,

state of our knowledge to say which is likely to prove the
best and most efficient machine for effecting these objects.

At an early period of my own history I made a model
of a vertical steam cultivator^ or a digging machine with
three spades intended to be propelled by steam^ and cutting
to a depth of ten to twelve inches. The spades were
worked by cranks and slides from the engine^ and the
boiler cylinders and other works were supported on a large
cast-iron roller and front wheel, which were moved forward
by the engine on the solid unbroken ground at a rate of speed
due to the action of the spades : these were suspended on
a frame on one side of the machine^ and turned over the
cuts as they were delivered by an inclined plane or pro-
jecting cam, which gave them an obliquity of motion in
their ascent from the ground after taking the cut. This
machine I had the honour to exhibit^ in 1813^ at the
Society of Arts and Manufactures, and the then existing
Board of Agriculture, where, I believe, it may yet be
seen. , ^ : *

From that period up to 1839, when Mir. Henry Pattes
proposed compressed air, or a vacuum, as an auxiliary for
conveying motion from a stationary engine to travelling
instruments fixed on a carriage^ nothing of moment had
been done ; and it is only recently that a movement has
been made in that direction.

Mr. J. Algernon Clarke, in his paper upon *^ The
Application of Steam Power to the Cultivation of the
Soil,** states that, *^ for making the steam engine itself an
agricultural locomotive we have Mr. Boydell's endless
railway engine, and the traction engine, which was exhi-
bited at the Salisbury Agricultural Meeting. It was
proved that it could climb considerable gradients; but
taking the weight of the engine with its water and coal
into consideration, I should question whether the sugges-
tions and improvements of Tuxford, Hally and Smith are

MR, fowler's plough. 173

ever likely to overcome the difficulties of rough surfaces
where so much of the power is expended in carrying the
engine itself forward over steep and unequal ground."

To overcome these difficulties, I apprehend we must
make the engine with a succession of fixtures along the
headlands, and have recourse to a windlass, or movable
pulley and rope, in order to compass the tillage of hilly or
unequal surfaces. This, I am persuaded, may be done
with economy and effect by the introduction of a suitable
engine and guide-pulleys made movable along the head-
lands* By this arrangement the whole power of the
engine would be applied to the ploughs, and the friction
consequent upon the drag of a considerable length of
rope.

Mr. Fowler has adopted this system, and, according to
returns received, it is stated that ** the working cost of
deeply breaking up the soil at five acres per diem, in-
cluding the shifting of the tackle, is 5s, 2d, ; and of trench-^
ing and subsoiling, three acres per diem, Ss. Sd. per acre ;
the wear and tear being taken at 1^. 6d, per acre more.
The price of the tackle and implements adapted to a com-
mon portable 7-horse engine is 220/., and the experience
of several farmers appears to show that it is worth while
to lay out this sum in order to derive full benefit from
the process." Mr. Smith of Deanston's method of turn-
ing the instrument at the end of its course is by simply
having it yoked to the ropes by a turn bow or hook in
front, an exceedingly simple and ready arrangement.

Mr. Clarke, in his paper, states rightly that the best
and indeed the first plan ever brought into actual opera-
tion is that of the engine and head gear on one headland,
and an anchorage and pulley on the other, both being
shifted along as the work proceeds. This is Mr. Fowler's
plan, and is that which was exhibited at Stirling, where
six and three-quarter acres were ploughed to a depth of

174 AGRICULTUBAX IMPLEMENTS.

five and a half inches at an estimated cost of ^s. per acre,
-which by horse labour would have cost 1 58. per acre. On
milder soils seven inches deep at the rate of nine and a
half acres a day cost 6«. an acre, which by horse labour
would have cost Ss. per acre. The trenching implement
going twelve inches deep, ploughed at the rate of five
acres per day at a cost of ll^. per acre, which would
require six horses in order to accomplish one acre per
day.

The saving may therefore be reckoned to be 35 per
cent, upon loamy land; 40 per cent, upon heavy land,
and 60 per cent, in the trenching process.

Such are the statements Mr. Clarke has given in his
paper, and assuming these returns to be correct we may
safely look forward to increased improvement and great
diminution of cost in the process of steam ploughing.

Again, referring to the experimental trials at Stirling,
I must not forget to notice the superior quality of the
work done, and the great advantage derived from turning
over the furrows at a rapid motion, thus dispensing with
the consolidating effects produced by the horses and other
damaging agencies affecting the soil as it leaves the mould
board of the plough. On this principle it will be observed
that only 800 yards of wire rope are required for plough-
ing 400 yards of furrow, and the price of the entire appa-
ratus for a 7-horse engine does not exceed 280/. The hands
required are only two men and three boys, exclusive of
water carriers. *

Numerous suggestions have been made in regard to the
above process, and I may be allowed to observe that what
is wanted is noi several ploughs attached to the drag rope
and guided by hand, but a series of ploughs fixed in a
frame or carriage with wheels, susceptible of being guided
in a straight line at a uniform depth from the surface over
which it is moved. A machine of this sort with the

REVOLVING CULTIVATOR. 175

ploughs tilting upon a centre and ploughing both ways is
adopted hj Mr. Fowler.

On this subject, Mr. Clarke observes, that we can
imagine no better plan than that of balancing two sets of
fixed ploughs upon a single pair of wheels. The frame
being hung midway upon the axles with a set of ploughs
at each end, is tilted so as to bring the hindmost set into
work, and when arrived at the headland the attendant has
simply to pull down the other end and start the implement
in its next course, and so on alternately moving the engine
and return pulley at the headlands until the work is
finished. A machine of this sort, attached to a portable
locomotive engine, such as is used for threshing, will, in
my opinion, meet all the requirements of steam tillage,
taking into account future improvements which are sure
to follow; and, I believe, it would prove a much more
economical process for the cultivation of the soil than the
system at present in use.

Some three or four years ago I was in communication
with Mr. Hoskyns on the subject of steam tillage, and in
order to carry out that gentleman's views I sent him a
rough sketch of a machine on the principle of rotation, with
cutters fixed on a revolving axis, placed behind the car-
riage of an engine, and of such a form as would enable them
to slice the soil, and by a spiral blade lay it in sections pre-
pared for the harrows, or any other process of pulverisation.
Not having heard from Mr. Hoskyns, I am not aware of
what has been done in this direction, but I am of opinion that
an effective machine of this kind might be applied with suc-
cess on lands which are level, or where the gradients are not
steep. The difficulties although not insurmountable are
considerable, as the weight of the engine and cutting appa-
ratus is a great drawback to this description of machine.

In the present state of our knowledge it is probably
difficult to determine the best principle on which steam

176 AGRICULTURAL IMPLEMENTS.

cultivation should be carried out. I am^ however^ decidedly
of opinion that a sum not exceeding 10^000/. would be
well spent by a commission of two or three gentlemen of
undoubted ability who would undertake the duty of in-
vestigating the subject, and instituting a series of experi-
ments calculated to ensure unmistakable results as to the
best means of overcoming the difficulties, and of establish-
ing a system of operations calculated to meet all the i*e-
quirements of a new, more perfect, and more economical
system of tillage.

Ten thousand pounds is a large sum to be expended for
such a purpose, but the agriculturists could not possibly
make a better investment ; and if this sum were raised by
subscription, with a small grant from the Government, the
Royal Agricultural and the Highland Societies, I am
satisfied the time would not be far distant when the re-
turns would be upwards of 30 to 50 per cent. I would
myself, with one or two others, gladly take charge of the
inquiry, and by careful experiment and research endeavour
to lay a basis for effecting the operations of the farm by
steam power at a rate of only one- third the present cost.

REAPING MACHINES.*

Machines of this kind are of great antiquity; they were
known to the Romans, and a graphic description is given
of them and their uses by Pliny. Those of modem date
have many properties which bear more of less directly upon
those of antiquity, but we hear nothing of them during
the dark or middle ages, and from these remote times up

* The subject of reaping machioes was carefiilly inyestigated in my re-
port addressed to Lord Stanley of Alderley, President of the Board of
Trade, and as that report contains the results of a series of experiments
made upon different machines at the Paris Exhibition, I have concluded that
I could not do better than submit it for your consideration. ^

BEAPING MACHINES. 177

to the present we have few traces of improvement^ or suc-
cessful attempts to substitute machine reaping for the
sickle. Various machines were invented in the early part
of the present century, though probably the first successful
attempt was made by Mr. Smith, of Deanston, in 1812.
This machine was followed by those of Ogle in 1822,
Mann in 1832, and Bell, of Carmyllie, Forfar, in 1826.
Mr. Bell has used his machine and gathered in his harvests
by it for the last thirty years, and it is not too much to say
that most of those now in use, both in this country and in
America, are based upon the principle which he introduced.
There is a great similarity in all these machines, and those
shown at the Universal Exhibition of Paris exhibited
nearly the same characteristics in principle and construe*
tion as those at the Exhibition of 185].

M^Cormick, Croskill, and others, introduced some slight
ttmprovements, but the principle of the machine remains
unaltered, excepting the receiving boards, which in those
brought forward for competition at the Paris Exhibition
are exceedingly variable in form and construction, and
some of them very ingenious. The period of the Uni-
versal Exhibition was most favourable for giving a faiir
trial to machines of this description, and the month of
August aflForded an excellent opportunity for testing their
merits by direct experiment. Through the liberality of M.
Dailly, a distinguished agriculturist and member of the jury,
a field of oats on his farm at La Trappe was set apart for
the exclusive purpose of ascertaining the properties and
proving the value of these machines. On the 2nd of
August, 1855, at 11 o'clock, the machines were divided into
three groups, and the contest for superiority commenced
as follows : —

178

AGBICULTtJBAL IMPLEMENTS.

l8t Group •<

2nd Group •

3rd Group

'Mr. Coamier*8 allotment

Mr. Wright's

Mr. Laurent's

Mr. Mazier's

Mr. Manny's

Mr. Crofikiirs
'Mr. M*Connick*8

Mr. Dray's

The Canad)iui

n
»1

Metres.
. 1628
. \7S3
. 1825
. 1826
. 1900
. 1958
. 1987
, 2250
, 1650

The points to be ascertained, in order to judge of the
merits of the machines, were, as far as I could learn, the
time required to cut the allotment, the number of hands
employed, and the perfection with which the work was
executed without injury to the grain. The first group
commenced operations by beat of drum at 11 o'clock, all
three machines starting at the same time.

Group 1. Cournier*8 machine (^French) y an BelVSf
principle.-^Thi& machine (with one horse) cuts clean, but
the cutters are liable to be entangled with straw, and a
great deal of time was lost from this cause. This defect
appears to be common to all the machines when the speed
happens to be reduced under two and a half miles per
hour. In this. respect I found the maximum velocity of
the machines to be as nearly as possible three miles an
hour, and the knives for every 18 feet in distance, that is,
for one revolution of the wheel, made 11 single or 22
double cuts. This machine had a sliding rake motion^
to enable the reaper to clear the receiving board of the
grain as it was cut. It might be improved and rendered
more effective, and would work much better with two
horses and a wider cutting board, so as to take a greater
width of grain and maintain the speed necessary to a
maximum velocity and a maximum result. From the
frequent clogging of the cutters it required 67 minutes
to cut 1628 square metres of com. In this machine

REAPING MACHINES. 179

the reel for gathering the corn went too fast, and in-
jured its working by striking the grain too high up the
stalk.

J. S, Wrighfs Automaton machine (^American) exe-
cuted 1733 square metres in 24 minutes. This machine
is nearly self-acting, requiring only a driver and one at*
tendant to follow the machine, in case anything should go
wrong. Its novelty consists in a rake worked from the
wheel that drives the cutter shaft ; it is attached by an
arm or connecting rod to the bevel wheel, and by a combi-
nation of levers receives a rotatory motion which, along with
that in a longitudinal direction, drags the grain forward over
the edge of the board ; in order, however, to make sure of
the discharge, another rake or cleaner strips the before-
mentioned one of its load, and lays the straw in parallel lines,
ready to be bound into sheaves. This machine, like Cour-
nier's, has some clever devices, but requires further altera-
tion to simplify and make it more effective and complete.

Laurent B French machine. — This machine, like Cour-*
nier's, was constantly choking with the straw around the
cutters. It is a copy of Bell's, and requires two men at
the pole, a driver, and a reaper, to work it It is a heavy
machine, and almost too much for two horses to work. The
falling off in the speed was the reason of its entanglement.
In all these machines speed is an element of success, as
whenever the velocity of the knives and the speed of the
machines was reduced, choking and entanglement of the
straw resulted. Under these circumstances, it is therefore
a consideration of much importance to have these machines
of such dimensions as to enable the horses to work them
with ease at the required velocity.

Group 2. Mazier^s machine {French). — This machine
is of light construction, adapted for one horse, and cuts a
breadth of 2 feet 7 inches in a line all round the field. It

180 AGRICULTURAL IMPLEMENTS.

cuts either right or left, by means of the frame containiDg
the cutters turning on a central axis. The knives are
worked by a wheel and worm, and are well calculated
to cut light grain, such as oats and barley, but might
prove inoperative on a field of heavy wheat. The ma-
chine, as a whole, was rather slender for the work it
had to perform, but if well constructed, and the parts
judiciously proportioned for two horses, there is no reason
why it should not reap any description of grain. In the
attempt to cut the allotment it unfortunately broke down,
some of the parts giving way.

J. H, Manny ( United States). — Mr. Manny's allotment
consisted of 1900 square metres, which was cut in 26
minutes. The machine is worked by two horses, and
cuts a breadth of 4 feet 6 inches. Mr. Manny speaks
highly of his machine, and gives numerous testimonials
of its efficiency, exclusive of medals, premiums, and
awards from different districts in America, and from
Various countries in Europe, for its performance. Ac-
cording to Mr. Manny's account, **it will cut either
grass or corn when downy wet or dry, and in whatever
direction the wind blows, without being stopped for a
single instant." He further observes "that it can in a
few seconds be converted from a reaper into a mower,
as the only thing required is to withdraw the platform
and change the knife of the reaper into the cutting
scythe of the mower."

^^ The cutting apparatus for com or grass is made in such
a way that it cuts as well backwards as forwards. When
the machine is reaping the wheat is received on the plat-
form, gathered, and put into a heap by the action of a wind
board, and by a single stroke of his rake the attendant
puts the grain down on the ground, at the back of the
machine, in the shape of already made sheaves, which
only require tying."

REAPIKG MACHINES. 181

' It will not be necessary to follow Mr. Manny in bis
description, which evinces great confidence in the supe-
rior performance of his machine ; suffice it to observe,
that it did its work moderately well, though some parts
were not clean cut.

CroskiWs machine (^English) is an improvement upon
Bell's, and in great repute among the farmers of the
North Eiding of Yorkshire and other parts of England.
In the hands of Croskill it has received several improve-
ments, but unfortunately on this occasion the key of the
connecting rod that works the knives got loose, dropped
out, and stopped the process of reaping ; under these cir-
cumstances it was considered advisable to withdraw the
machine, and leave the field open to other competitors.

Group 3. M^CormicKs machine {American^. — This
reaper is probably one of the best machines of its class.
It reaped 1987 square metres in 17 minutes, and judging,
not only from the quantity of work done in so short a time,
but from the manner in which the ground was cleared and
the grain cut, it evidenced much greater perfection in its
operations than any of the others whose powers were
brought to the test.

It cuts a clean track of 5 feet 6 inches wide, and per-
forms the operation with a degree of certainty and preci-
sion sufficient to account for the very short time in which
the allotment was cut. This machine, however, like most
others, is susceptible of still further improvements, and I
am glad to find that Messrs. Burgess and Key, the makers,
are about to introduce a new movable apparatus, consist-
ing of Archimedean screws, for delivering the grain from
off the receiving board as it is cut. This would render the
machine' much more perfect, as its great defect was the
way in which the grain was delivered from the platform,
and the evident want of some method of laying the heads

N 3

182 AOBICtJLTURAL MACHINJlS,

and straw parallel^ and in bundles or sheaves^ and so as to
clear the track for the horses on the return cut.

JVm. M. Dray and Co.^s machine (^English) is of an ex-
ceedingly compact form. It is entirely without a reel for
gathering in the corn to the cutters^ and requires only one
man as a reaper to watch the cutters and discharge the com
as it is received upon the board or wooden platform behind.
The cutters are five feet wide, and it reaped 2250
square metres in 35 minutes. The peculiar features of
this machine are its portable construction^ and the receiv-
ing board which moves upon an axis^ and is tilted by the
pressure of the reaper's foot, so that the grain drops be*
hind ready for the person who follows to bind and tie
it up.

The only objection to this process is that it requires
the binding to be done immediately, "otherwise the work-
ing of the machine would be impeded, and the horses at
every succeeding cut would have to trample over that pre-
viously reaped. This appears to be the chief defect in the
machine ; a different clearing apparatus to effect the dis-
charge of the cut grain in a lateral direction would render
it much more valuable. It would give time for binding
up the grain into sheaves, and at the same time it would
clear the track for the horses and machine in their return
for the next cut.

The last machine (Canadian) was withdrawn from some
cause not explained.

The following Table, which Mr. Edward Coombes got
up at my request, exhibits the results of the different
trials.

STBENGTH OP PAETS.

183

Trial of Reaping Machines on the farm of Mr, Daillr/^
at La Trappe^^ near PariSy 2nd August 1855.

Breadth

No. of

•

*& «

•

Maker's
name.

Country.

cutting

imrt.

square
metres
cut.

s
£

Remarks.

It. in.

Coumier .

France .

4 3

1628

Driring-wheel 3' 3" ; crank
makes 1 1 revolutions to 1
of the wheel ; knife not
serrated.

J. S. Wright

U.S.
America

5 3

1733

Diameter of drlring-wheel
A' A" ; crank makes 24 to 1.

Laurent .

France .

1826

Diametfr of driving-wheel
3 reet ; crank makes 1 5 to 1
(similar to Bell's).

Masier . .

France .

2 7

Broke down

•.M

Small machlnt*. cutting right

or left. Knives worked by

wheel and worm.

Manny . .

U.S.

America

4 6

1900

Diameter of driring-wheel
2' 6" ; crank makes 13 to 1.

Crnskill .

England
U.S.

Broke down

M*Cormick

5 6

1987

America

Dray . . England

2250

Canadian machine .

6 6 Withdrawn

2 —

On a careful examination of the machines entered for
the prizes, it should be observed that in every one of
them an attempt was made to effect a certain purpose
by means of transmission calculated to retard rather than
to facilitate the process of cutting. It is true that in ma-
chines of this kind, where horses are employed as a
motive power, it is desirable to make the parts as light
as possible, and to effect the motion of cutting, &c. with
as light wheels and motions as can be made. But the
small wheels and their attachments, as applied to these
machines, appear to me to be the very worst and heaviest
parts of the machine, and I would earnestly urge
upon the makers of reaping machines the absolute neces-
sity of increasing the dimensions of the gearing which
works the cutters, and at the same time that the journals
and ends of the shafts should be attached to one casting f
80 that they cannot vary in position, but must movei

N 4

184 AGBICULTUBAL MACHINES.

and, speaking technically, come and go with the machine.
These alterations being made, and proper clearing ap-
paratus attached to the receiving -boards, we might then
reasonably expect the machines to perform the labours of
the harvest with much greater certainty and rapidity than
is at present possible.

From the above Table it will be seen that M^Cormick's
American machine performed the most work in the least
time ; that Wright's and Manny's executed as nearly as pos-
sible the same quantity of work in the same time, there being
a fraction in favour of Manny ; and that after these Dray
was next in the order of time and quantity of work done.

Reducing the whole work done to a standard of 2000
square metres^ the competing machines will stand thus :- —

Mean.
25-81.

M*Connick'8

would cut

Metres.
2000

Minntes.

17-ir

Manny's
Wright's
Dray's

2000
2000
2000

27-36
27-69
31-11

• In the investigation of this subject we have hitherto
confined our observations to the machines. There is,
however, another element equally important and essential
to the eflSciency of the process of machine reaping, and
that is the preparation of the land; and in fact before
we can look forward to complete success, the surface of
the soil must be levelled and the present injurious system
of ridges done away with. To apply machinery to the
labours of the farm, the land must be prepared not for
hand but for machine culture, and the successful intro-
duction of reaping machines will chiefly depend upon the
preparations that are made for their reception. The
system of ridges may be tolerated and overcome with
the sickle, but to give to the new process of reaping by
machinery its full value, a totally different plan of opera-
tions must be pursued, and the fields laid down with a

DUTY OF THE FAEMER. 185

perfectly smooth surface. The larger description of stones
and other obstructions should be removed, and in place
of the superfluous waters not required for the nourish-
ment of the plants being allowed to flow between the
ridges on the surface of the field, sweeping in heavy
showers everything before them, the new system of
drainage must be adopted, and the water carried under
in place of running over the surface.

To make a machine, such as a reaping machine work
well, everything must not be left to it, the agriculturist
must do his duty as well as the engineer ; and that duty
duly performed on both sides will secure certainty of action,
solve the great problem of machine labour, and effect
satisfactory results. When this is accomplished, and not
till then, we may look forward to the crops being well and
quickly gathered in by machinery, to the exclusion of a
laborious process effected with diflSculty and often im-
perfectly by the human hand. One of the greatest
advantages of machine over manual labour is the great
saving of time effected by the former, and this alone is of
vast importance in countries like England where the
climate is variable, and where a whole harvest may be lost
or seriously damaged by a wet season, unless rapidly
cut and stored. At such times the machine reaper
becomes invaluable, and cannot fail, when properly con-
structed and properly applied, to prove a great national
benefit.

186

LECTURE III.

ON THE KISE OF CIVIL AND MECHANICAL ENGINEERING^
AND ITS PROGRESS TO THE PRESENT CENTURY.

It is instructive to learn from history how men lived
during remote periods when the great names of antiquity
flourished ; to note the condition of our own forefathers^
and to trace the course of mechanical improvement in
its connection with human progress in all its stages.
During the dark ages of a nation's history, before it has
emerged from the clouds of barbarism, what few mecha-
nical contrivances exist are rude and imperfect, and ill
calculated to alleviate the toil of hard manual labour ; but
when a movement in advance has been made, and civilisa-
tion dawns more brightly, it becomes highly interesting to
walk side by side with the great men to whom that pro-
gress is due, and to follow them through all the troubles
and difficulties they had to encounter in the pursuit of
knowledge and the introduction of mechanical aids and
substitutes for labour in the operations of daily life.

Let us consider the subject for a moment, and briefly
examine the condition of the difierent races to whom we
are indebted for many of the blessings we now enjoy, and
from whom we have derived mechanical aids that have
come down to us from remote periods of the world's
history.

STATIONARY CIVILISATION. 187

CONDITION OF CONSTRUCTIVE ART IN VARIOUS NATIONS
DOWN TO THE SEVENTEENTH CENTURY.

Some nations, such as the Chinese and Hindoos, at-
tained a comparatively high state of civilisation for ages
antecedent to the conquests of the Greeks and Bomans.
The plough, the spindle, and the loom have been known to
ancient nations from the earliest times. Astronomy,
geometry, mathematics, and other branches of science were
cultivated by those people to some extent, and many of the
useful arts were successfully practised, but that upon a
scale better adapted to the supply of their ordinary wants
than indicative of a rate of progress calculated to develope
to any great extent the inventive faculties of the age in
which they lived. Such was the position of the oriental
nations more than a thousand years before the Christian
era; and looking to the advancement which they might
have attained in science and art, it is lamentable to find
that their progress was checked by conquest and bad go-
vernment, and that they have since become a stationary
people.

What, then, is the cause of this non-progression, which
for thousands of years has locked up the inventive facul-
ties of races to whom we are indebted for the first princi-
ples of science and the rudiments of civilisation? Probably
we shall not find it to have arisen from any natural defi-
ciency, nor from the want of those higher powers of intellect
which constitute genius in every age and country ; on the
contrary, we may trace the absence of progress and the
national decline to a stationary and restrictive principle of
government, united with religious dogmas and a decaying
faith, which effectually deaden the inventive faculties, and
paralyse the energies of an otherwise gifted people.

That these obstacles have existed from the earliest
periods is evident, and that they still operate is observable

188 RISE OF CONSTRUCTIVE ART.

at the present time in many countries where the govern-
ment is absolute. The Chinese, for example, are the same
people at the present day that they were in the age of
Confucius, and they may continue so for many ages to
come, unless roused to action by subjection to a foreign
power, or some other cause calculated to bring them under
the influence of western civilisation. The Mahommedan
successors of Timour, and the followers of the prophet,
are equally adverse to change ; and so long as a prescribed
form of government exists, associated with an intolerant
creed, we may look in vain for that progress which is so
happily attained amongst the more cultivated intellects of
the west.

The Orientals have long ceased to exercise any influ*
ence upon the development of civilisation in other coun-
tries. It is evident, however, that Egypt attained at an
early period a high degree of refinement, and gave a
marked impetus to the arts in all surrounding countries.
It is evident, from the quantities of linen which have been
discovered shrouding the remains of their rich or distin-
guished men, that spinning and weaving were largely
practised by the Egyptians, and judging from the splendid
remains of their temples, pyramids, and public buildings,
we may reasonably infer that practical science and useful
art were largely cultivated, and applied in the construction
and erection of these vast memorials of antiquity, which
have stood the test of time for ages almost unimpaired.
In the irrigation and tillage of the soil the Egyptians must
have attained considerable perfection, and the quantity of
wheat grown and exported indicates the industry of the
Egyptian people and the great fertility of the soil.

From the Egyptians we descend to a people who, of all
others, ancient or modern, have excelled in the refine-
ments of architecture and sculpture. To the Greeks we
owe the application of the true principles of harmony in

THE ROMANS. ISft

these arts^ and the development of beauty of design and
symmetry of proportion. That illustrious people were no
copyists of the art of surrounding nations^ but were per*
fectly original, and struck out for themselves new concep-
tions in design and construction. They made the profound
and loving study of nature the high toad to perfection,
and rendered symmetry.in the development of natural forms
the grand criterion by which the artist was judged. These
were the characteristics of ancient Greece, and with all
our boasted powers of invention we have never been able,
up to the present time, to originate anything comparable
in beauty to the five orders of architecture as they came
from the hands of the Greeks.

How unfortunate has it been for art and for the world
that the constant wars and contentions amongst the Greek
states, against the Macedonian and other powers, should
have retarded the progress of the useful arts, and ultimately
sapped the liberties of the Grecian people, destroyed every
hope of further improvement, and left them an easy conquest
to the rising and more powerful republic of the Eomans.

To the Biomans, who shortly after the conquest of
Greece became masters of Europe, we are indebted for
many works of art and mechanical adaptation. It is sup-
posed that water, as a motive power, and wheels with
buckets and floats, were applied by them in grinding corn
and pumping water. Of their corn-mills, some were on
the principle of the pestle and mortar, and others consisted,
like our own, of revolving stones. Some of these latter
mills are yet to be seen in the baker's house which has
been uncovered at Pompeii, where I had the opportunity
of sketching one about a year since. Fig. 28 will explain
the principle of these interesting remains. A is a block of
rough leucitic lava, cut into a conical form, with an iron
pivot at the top, which supports the movable stone B,
composed of the same material, and hollowed out to em-

J90 EI8B OP CONSTHDCTIVB ABT.

brace the conical fixed stone A. The upper part was
mmilarly hollowed to form the hopper c, from which the
corn, passing by degrees down between the abrading sur-
faces of A and B, as the mill was worked, was crushed to
powder. It is not certtun in what way motion was im-
parted to the mniring stone, but I am inclined to think
from the number of stones of this kind, placed in close
proximity, that the grinding process was effected by a see-
saw motion, produced by slaves working at the extended
Fig. 28.

poles D D, which are fixed in the sockets in the upper
stone. The bran was probably separated from the flour
by means of a sieve ; and it may be remarked that in the
same building with the mills, at Pompeii, the ovens may
still be seen, built of brick, almost in every respect similar
in form to those in use in this country.

There can be no doubt as to the fact that the Itomans prac-

ITALY, 191

tised the arts of spinning and weaving, but, generally speak-
ing, they were rather the patrons than the cultivators of
art ; and whether we view them as agriculturists, architects,
or mechanics, we shall find that the great works in Rome,
and in the Roman towns of Italy, were designed and
executed by foreigners, and chiefly by the Greeks and
Tuscans. The Romans laid the whole of their vast con-
quered possessions under contribution for the gratification
of their own ambition and the enrichment of their own
homes and cities. The results of their conquests are still
to be seen in the magnificent remains of monuments and
edifices, and works of public utility scattered throughout
Italy and the provinces. The scenes of rapine and murder
which were enacted during the latter days of the empire,
and the consequent insecurity of life and property, with
the increasing luxury and indolence of the people, readily
account for the stagnation of useful art which preceded the
decay of the empire.

The consideration of the state of art amongst the Ro-
mans brings us down to the period of Alaric and his suc-
cessors, when the empire was destroyed by the inroads
of the Northern barbarians, and all progress in the arts
stayed for almost a thousand years. About the beginning
or middle of the fifteenth century, and during the Italian
Republics, the light of civilisation began again to dawn
upon a new generation of men. In 1474 was born Michael
Angelo Buonarotti, one of the greatest painters, sculp-
tors, and architects of any time ; one of the ablest de*-
signers, and a skilful anatomist. His works are celebrated
throughout all Europe, and the beauty of his paintings
and the originality of his conceptions in the highest regions
of art, are to this day the subjects of universal admiration.

After Michael Angelo came Galileo, bom in 1564, and
to that great man we owe the telescope and pendulum, ap-
plied by his son Vincenzio to the regulation of the clock. He

192 RISE OF CONSTRUCTIVE ART.

was oneof thefirstof the school of experimental philosophers
who, abandoning the barren methods of the schoolmen^
have produced such brilliant results in physical science.

Michael Angelo in the fine arts, and Gralileo as the
representative of theoretical and experimental science^
were followed by those who in our own country led the
van of progress in another department. The Marquis
of Worcester, in his " Century of Inventions," announced
the steam engine ; and however crude his invention may
have been, it must still be taken as the starting point
from which have sprung the vast developments of steam
power. The Marquis actually erected one of his engines
of about 2-horse power on the banks of the Thames, and
it was employed in supplying the town with water.

In " The Journal of the Visit to England of Cosmo
de Medicis, Grand Duke of Tuscany," in 1699, there is
an interesting record of this engine of Worcester's. *' His
highness," writes his secretary, ** went again after dinner
to the other side of the city, extending his isxcursion as
far as Yauxhall, beyond the palace of the archbishop of
Canterbury, to see an hydraulic machine, invented by my
Lord Somerset, Marquis of Worcester. It raises water
more than forty geometrical feet, by the power of one man
only ; and in a very short space of time will draw up four
vessels of water, through a tube or channel not more than
a span in width, on which account it is considered to be of
greater service to the public than the other machine near
Somerset House."

This interesting document proves that the plans of the
Marquis were practical and capable of advantageous em-
ployment. Yet it was reserved for Captain Savery to
introduce steam generally as a means of raising water.
Savery's engine, of which fig. 29 is a sketch, consisted of
two boilers, in which the necessary steam was generated,
and two receivers with valves, which were placed at the
bottom of the mine shaft, about thirty feet above the

SATEET AHP PAPIN.

■water to be drniDed, as at a. The
procees of pumping was effected by
admitting steam into one of the re-
ceivers, as a, and then cutting off the
connection with the boiler. The eteam
was suddenly condensed by meane of
a jet of cold water, which, forming a
vacuum, the water to be lifted imme-
diately rushed up the pipe i, by atmo-
spheric pressure, to refill the receiver.
Steam being then admitted from the
boiler to press upon the water in the
receiver, and all connection with b being
cut off by a valve, the water was forced
up the pipe c, and discbai^d into the
trough d. The steam in a being then
sgun condensed, the process was re-
peated, and thus by the alternate action
of two receivcFB a continuous stream
was maintained.

Dr. Fapin shortly after this made
some contributions to our knowledge
of the properties of eteam by his ex-
periments with the cylinder and piston,
and by the invention of the digester,
in which he dissolved bones and other
animal solids by means of the high tem-
perature which water attains under
great pressure. It is upon these re-
searches of Papin that Arago* (in his
£loge of Watt) and other French philo-
sophers, have founded his claim to the

■ Anigo's Biographies of diiCiagnMied Scien-
tific Uen, p. 604.

194 FROQBESS OF ENOINEEBIITQ.

inTention of the steam engine. I have taken some puna
to inquire into the justice of tbie oBBertion and find the
claim to be altc^ether baseless, and to depend entirely
upon the construction of a small model which could never
have been ueed for any practical purpose, and cannot be
shown to have had any influence on the actual introdac
tion of the steam engine.

Savery's engine, attended as it was by such an enoimous

Fig. 30.

THE ATMOSPHERIC ENGINE. 195

waste of steam^ was shortly afterwards superseded by that
of Newcomen, a far more perfect and economical ma-
chine. This engine, introduced in 1705, is well known as
llie atmospheric engine, having an open-top cylinder, that
the atmosphere may press freely upon the upper side of the
piston. Fig. 30 represents a large engine on the New-
comen principle, constructed by Smeaton in 1775, at
Chasewater; c is the cylinder 72 inches in diameter,
with its piston of iron coated with wood, it is placed im-
mediately over the boiler J, with which it is in communi-
cation ; a a is a pipe for the injection water for condensing
the steam, supplied by the pump d from the cold water
cistern ; the reciprocating motion of the piston, e, is com-
municated through the huge timber main working beam
//, to the pump rods g g, which pass down the mine shaft.
In working this engine, the steam was first admitted into
the cylinder c, and with the weight of the pump rods
g g immediately dragged the piston to the top of the
stroke ; a forked rod, worked by the engine, then shut off
the communication of the boiler, and opened the cold
water injection cock a, the result of which was the sudden
condensation of the steam in the cylinder, and the forma-
tion of a vacuum under the piston ; when the pressure of
the atmosphere forced down the piston and completed the
down stroke, raising at the same time the buckets and
plungers of the pumps in the mine, the steam was then
readmitted, and the process repeated for every stroke all the
day through. * Now it is evident that every time the injec-

* For comparison with other engines, to which reference may be made,
we may add the dimensions of this, which was the largest engine Smeaton
had seen : —

Cylinder 72 inches diameter.

Stroke 9 feet.

Making from 4 to 9 strokes per minnte.
Actual power . . . .150 horses.
Meporta of John SmeaUmf YoL ii. p. 347.

o 2

196 FBOGBESS OF ENGINEEBING.

tion water is admitted the cylinder is cooled^ and requires to
be heated again at the expense of the steam before another
stroke can be effected. This waste of steam with a pro-
portionate expenditure of fuel did not escape the penetra-
tion of Watt^ and first led him to those modifications
which ultimately resulted in the double action engine as at
present constructed.

In the earlier engines, the alternate admission of the
steam and injection water was effected by hand^ by means
of cocks, but was afterwards more ingeniously accom-
plished by the contrivance of the boy Humphrey Potter,
who to save himself trouble and gain time to spend with
his playfellows, attached strings to the cocks or valves, and
caused the main beam of the en^ne to open and shut them
in the ascent and descent of the stroke. Mr. Beighton
availed himself of this ingenious contrivance, and made
the engine self-acting, by fixing gearing to the valves,
worked by plug rods instead of Potter's strings. Potter
was, however, the original inventor of self-acting gear,
and although we cannot quite approve this breach of duty
to which a game of marbles tempted the little fellow, yet
we must admit that as a juvenile engineer be was no
bad example, when such a man as Beighton adopted his
invention, and turned it so successfully to account in
rendering the engine thenceforward self-acting.

MILLWOBK PBOM 1700 TO 1800.

The condition of mechanical art contemporaneously with
these inventions, is exhibited in a work entitled Machines
et Inventions approuvees par VAcadimie Royale des Sciences,
which records most of the new discoveries in practical
science from 1688 to 1734, a period of nearly half a cen-
tury. Most of these inventions are exceedingly crude and
imperfect, but some are ingenious and curious. Amongst

MILL WORK. 197

them we find an immense number of schemes for grinding
com, pumping water, sawing wood, propelling vessels,
boring cannon, rolling lead, &c. They also contain draw-
ings of the earliest forms of the steam engine.

The use of cast iron and bevil wheels appears not to
have become general until the latter part of the last cen-
tury. The whole of Smeaton*s designs for mills from the
commencement of his career to 1782 exhibit only the
** cog and rung," or wheel and trundle arrangement.

Fig. 31 represents an oil mill, with overshot water-wheel,
constructed by Smeaton in 1776, and is a good example
of the millwork of the period. The water wheel a a is
carried upon a solid cast iron axis b &, and its movement
is transferred by means of the spur-wheel c, and trundle
or wallower d^ to the horizontal shaft A A, and again by
the spur cog-wheels Cyfy to the vertical shaft which carries
the heavy oil stones g g. It may be observed that the
water for this wheel was actually raised by a steam engine,
no more direct mode being then known of converting the
reciprocating action of the piston and cylinder into the
rotatory movement required by machinery.*

In Smeaton's time the shafts were made almost univer-
sally of wood hooped with iron, and with gudgeons of the
same material, sometimes turned and sometimes not,
running in a block of hard wood, or a lump of whinstone,
as best suited the convenience of the millwright. Cast
iron in millwork began to be introduced about 1770-80.
The first bevel wheel seen in Scotland was at a corn mill
in Ayrshire about 1770, and the same wheel was retained

• With an engine properly constructed, of twenty-five inches cylinder,
I can undertake to raise to the height of thirty feet, 1000 gallons, wine mea-
sure, per minute, with the expense of 1 cwt. 3 qrs. coals per hour, and I do
apprehend that if a new engine were set about in conjunction with this mill,
that such an engine would be made for 350/. or thereabouts. — Smeaton*a
ReportSi yoL IL p. 401.

o 3

198 PROOBESS OF EITOINEEEINO.

as ft reliC) forming part of a dial stand in front of the houBO
of Mr, Murdock of Soho. Arkwrigbt is B&iA to have
used bevel wheels of iron on a small scale in 1775, and ui

MILLWOBK.

199

the Albion Mills, erected in 1783 and 1784, of which the
millwork is due to John Bennie, the whole of the wheels
and shafts, including the bevel wheels for driving the
upright shaft, were of cast iron. The exact period when
bevel wheels became general is uncertain, but the wheel
and trundle disappeared during the days of Andrew Meikle
and his successor John Bennie. At a later period still
cast iron for shafting was in turn superseded by wrought
iron, a change in the carrying out of which I myself took
an active part. I can recollect the ponderous drums and
heavy shafts of former days, which used to utter groans
and complaints at every revolution. Such a shaft with its
wooden drum is shown in fig. 32, as it existed in many of

Fig. 32.

Fig. 33.

our cotton mills only fifty years ago, and fig. 33 exhibits
its modem descendant of polished wrought iron, about
which I may have more to say in the next lecture.

These remarks bring us to a period in the history of the
useful arts from which we may date the commencement of
those improvements and discoveries in mechanical science
which have effected a change in the condition of men of
aU countries, and from which we now reap benefits un*

o 4

200 PROGBESS OF ENGINEEBIXa.

known to the generations of the past. To what extent
these discoveries may yet he carried, it is not for me to
determine, but looking at the great perfection at which
mechanical science has already arrived, he would be a
bold man indeed who would venture to set limits to the
development of human invention. In directing your atten-
tion to the important events that have occurred from time
to time during the past and present century, I shall divide
the subject into two periods — the first extending from 1750
to 1800 ; the second from 1800 to the present time.

ENGINEEBING DURING THE LATTER HALF OF THE

EIGHTEENTH CENTURY.

At the commencement of 1750 the title of engineer was
unknown in the vocabulary of science ; it was reserved for
Brindley and Smeaton to establish a distinct profession
under that name. Previously to that time the engineering
of the country was chiefly effected by architects. Inigo
Jones designed a bridge of three arches in 1636 ; Labelye
built Westminster Bridge, and Mr. R. Mylne, the father
of the present engineer of that name, built Blackfriars,
which was commenced in 1760 and finished in 1771.
From that time to the present nearly the whole of the
bridges of this country have been built by engineers.

One of the most successful bridge-builders and engineers
of his time was Smeaton, who, at the early age of eighteen,
had made himself acquainted with practical mechanics,
and devised some ingenious contrivances for measuring a
ship's way in the water. In 1753 he was elected a Fellow
of the Royal Society, and in 1759 he was honoured with
the Society's gold medal for his paper " On the natural
powers of water and wind to turn millsJ*^ In 1759 he com-
pleted the Eddystone Lighthouse, which for a hundred
years has resisted the storms of the Atlantic ; a work of

SMEATON AND BRINDLET; 201

great difficulty, that has not been surpassed by any simi-
lar construction up to the present time. From 1759 to

1764 he appears to have to some extent retired from
active engagements, as we hfar little of him tiU the con-
struction of the bridge at Perth, which was begun in

1765 and finished in 1771. From that time till his death
in 1792 he was the leading engineer of the kingdom. He
made the river Calder navigable, planned and completed
the navigation of the great Forth and Clyde Canal ; erected
the blowing machinery at the Carron Iron Works ; and
there was no man of his time who constructed so many mills
or introduced into that department of mechanical con«
struction so much talent or so many improvements. Mr.
Smeaton never trusted to theory where he had the power
and the means of testing his improvements by experiment.
His experiments were the basis on which he founded his
constructions ; he never trusted to chance, and hence his
success. We owe him a debt of gratitude for many dis-
coveries and improvements, and may consider him the
father of engineering; the model on which his successors
Rennie and Telford were moulded.

In the same field of study and industry was Brindley,
the constructor of the Bridgewater Canal, one of nature's
engineers. No two men could be more dissimilar in taste
and character than Smeaton and Brindley ; yet both were
men who left behind them lasting monuments of their
resources, and although they commenced their career
under difierent auspices, — the one as an attorney — the
other as a working millwright with no education,—
both of them attained eminence in the double capacity
of mechanists and civil engineers. Brindley was bom at
Tunsted, in Derbyshire, in 1716, and laboured hard for
a livelihood till seventeen years of age. Having a taste
for mechanical pursuits he bound himself to a millwright,
and during his apprenticeship obtained the confidence of

202 PBOGBB88 OF EKGINBEBIKG.

his employer^ of whom he eventually became the instructor.
He then commenced business on his own account, and such
were his inventions and contrivances that constant employ-
ment was secured him to an extent never realised by any of
his predecessors. In this way he laboured successfully till
he was forty years of age, and during that period, amongst
other works, he erected at Clifton, near Manchester, a
water engine for draining a coal mine, a silk mill at Con-
gleton, and various other constructions conddered at that
time of great importance. At Newcastle*under-Lyne he
erected a steam engine, the boiler of which was made of
brick, and the cylinder of wood hooped with iron. How
this engine worked, we are not informed ; but the whole
scheme was opposed and ultimately swamped by some
interested competitors. The crowning efforts of Brindley'a
genius, however, were the Great Bridgewater Canal, and
the viaduct across the Irwell, at a height of forty feet
above the river, by which he effected a communication
between Manchester, Worsley and Buncom. This great
work was begun in 17 '^9, and the first boat entered Man-
chester in 1762. Amongst other similar works executed
by Brindley, was the Union or Great Trunk Canal, be-
tween the Trent and the Mersey. After this time the
country was penetrated in every direction by canals ; some
constructed by Brindley, Jessop, and Smeaton, and others
of later date by Bennie and Telford.

In the construction of canals, millwork, and water
engines for rusing coal from the mines (some of which are
still in existence between Worsley and Bolton), Brindley
was without an equal ; and the country is indebted to his
genius for penetrating mountains by tunnels, and for con-
veying navigable waterways over rivers by those aqueducts
which give to the canal system the novel feature of a river
suspended upon arches high in the air, with vessels float-
ing upon it| above others on the river below. By the

EXAMPLES OF SUCCESS. 203

fertile resources and indomitable perseverance of this dis-
tinguished and self-taught engineer^ all these objects were
attained in the face of difficulties sufficient to discourage
the ablest and best educated men of the age in which he
lived.

And I would here remark for the benefit of the young
men now before me^ that this brief and imperfect review
of the career of our two first engineers ought to teach us
that the only road to fame and distinction in our respective
professions is through the portals of persevering industry.
In that arena we must labour^ and in that field expand our
intellects and mature our understandings^ not by looking
on» but as hard workers in the pursuit of knowledge and
in the exercise of our callings. It is immaterial what pro-
fession or business you pursue ; to succeed in it you must
work, and to become a leader you must throw the whole
of your powers, physical and mental, into the contest,
otherwise you are sure to lose and to be distanced in
the race. To become a great man you must be a hard
worker, and I can tell you from experience that there
is no labour so sweet, none so consolatory, as that
which is foimded upon an honest, straightforward, and
honourable ambition. Take for your examples the two
great men I have brought under your notice, and let
their actions stimulate you to exertion in the paths of
honest and persevering industry.

THE STEAM ENGINE, AND THE BESULTS OF ITS
EMPLOYMENT SINCE THE TIME OF WATT.

I must, however, observe that Brindley and Smeaton
are not the only men to whom the country and the world
are indebted for the commencement of a new era in
mechanical progress. Other labourers were in the field.

204 PBOGRESS OF EN6INEERIK6.

of a character equals if not superior^ in inventive talent to
either of them. To Watt and Arkwright we owe a debt
of gratitude which we shall never sufficiently repay. We
may write their histories, or raise monuments to their
memories, but these are of little moment when com-
pared with the splendid results which have flowed from
their discoveries, and influenced the relative positions of
the whole human race. If we compare the steam-engine
as it left the hands of Watt, with its puny condition and
restricted applicability when he first became acquainted
with it, we are lost in amazement at the extent of its
power, the beauty of its construction, the docility with
which it adapts itself to all circumstances; and all these
qualities are due to him and to him alone.

At the present time there exists in the British empire a
total steam power equivalent to that of more than 8,000,000
horses, working ten hours a day ; or if we add to this the
engines afloat we have a total of 1 1,000,000 of horse-power,
a force vastly exceeding that of all the living horses in the
kingdom. Compare the state of our manufactures, the
extent of our commerce, the facilities of transport which
we now enjoy, with the same in the early days of Watt,
and tell me whether this amazing increase, this immense
development of our resources, is not owing to his genius ?

It is impossible to form a just conception of the benefits
that have arisen from the introduction of the steam engine.
It is applicable to every condition in life, and has multi-
plied the material comforts of mankind to an extent with-
out a parallel in the history of nations. It has given a
subsistence to millions who but for it would never have
existed, and it has given employment to thousands of
an intellectual character which no other means could
have furnished to the same extent. Now in every
country where coal, wood, and water are found, industry
may flourish, and the steam engine be in constant de-

THE INFLUENCE OF STEAM. 205

xnand. If time permitted, I would cheerfully venture
upon a description of the improvements which have been
effected in this important machine since the days of Watt,
but I have trespassed too long upon your patience, and
must curtail my observations within the narrowest limits.

Notwithstanding the variety of forms into which it has
been moulded, the steam engine is still the same machine
in all its simplicity of principle as when it came from the
hand of Watt ; it has the same reciprocating action, the
same principles of separate condensation, and the same
mechanical organisation as it had seventy years ago. What
can exceed in beauty of contrivance the parallel motion,
the governor, and other motions by which this wonderful
machine is rendered effective. Innumerable attempts have
been made at its improvement, and yet with the exception
of working high pressure steam expansively, and by this
means economising fuel, there has been no change in the
principle of the steam engine, either in its condensing or
non-condensing form. It is still the engine of Watt ; his
name is stamped as indelibly upon it as Newton's upon the
law of gravitation.

In former days many persons looked upon the invention
of the steam engine as a social misfortune. If we would
credit these imbecile philosophers, the introduction of every
machine is an injury rather than a benefit, and the wonder-
ful combinations which we are accustomed to admire for the
regularity and harmony of their movements are instruments
of mischief, and ought to be proscribed. There can be no
greater fallacy than this; the working of our mines, the
extension of manufactures, and the immense increase of
industrial pursuits, fully testify to the immense advantages
which mankind have derived from mechanical contrivances.
In this country alone they have given employment and
social comfort to millions of the labouring poor, and they
have raised the country to a degree of wealth, influence.

206 FQOGRESS OF EKGINEEBING.

and power, greater than she ever before attained in her
most promising days of prosperity.

If I had the means at my disposal I would lay before you
correct statistics of the steam power which has thus raised
our resources in the different departments of mining, manu-
factures, and transport. Sufficient data are not, however,
accessible ; but I have estimated the total in round num-
bers at 11,000|000 horses^ working ten hours per day.
Thatii

Employed In Nominal Horse Power. :

Mining and the maniifactiire of metal • . . 450,000

Manufactures 1,350,000

Steam nayigation 850,000

Locomotion 1,000,000

Total 3,650,000

And as these engines are worked at an average of three
times their nominal power, the above numbers represent a
force equivalent to eleven millions of horses; and taking
one person to every nominal horse-power, we shall then
bave nearly four millions of people to whom the steam
engine is giving employment in Great Britain and on
board our ships. It is no wonder, therefore, that we
revere the memory of Watt, when we look upon the
benefits he has conferred upon the world and upon his
country.

The Cotton Trade. — To Richard Arkwright, an
ingenious barber, belongs almost exclusively the merit
of those inventions which gave an important impetus to
the development of an entirely new branch of industry.
The carding, drawing, and spinning of cotton, which
eighty or ninety years ago was performed by hand,
being spun upon a single spindle, is now increased a
million fold, and the value of the cotton manufacture
has increased from 2,000,000/. to upwards of 60,000,000i
per annum, being in the ratio of 30 to 1. Upwards of

COTTON MACHINERY. 207

1,600,000 bales of cotton were imported into Liverpool in
1857, and the improvements which have followed Ark-
wright's original inventions have raised the country, with
the aid of the steam engine, to her present high state of
prosperity.

The late Mr. Kennedy states that the first improvement
consisted in the division of carding and spinning into two
distinct operations, and progress was first made in the
carding, by means of which one boy or girl could work
two pairs of stock cards. This continued for a short
time, when further improvements followed, until one
person could work four or five pairs by holding hand
cards against stock cards fixed on a cylinder revolving
on its axis, or what is now called a carding machine,
the inventor of which is unknown. Next in order came
the invention of Hargreaves in 1767, namely, the spinning
jenny, by means of which a young person could work from
ten to twenty spindles at once. After Hargreaves came
Arkwright, whose first mill was built at Cromford in this
county (Derbyshire) in 1771, and in 1780 appeared a
valuable machine called ** Hall-i'-th'-wood," but now
"Crompton's Mule," from its uniting the qualities of
Hargreaves' and Arkwright's frames.

In the department of weaving we are indebted to Mr.
John Kay of Bury for the fiying shuttle, which he intro-
duced about the year 1750. This was followed by the
improvements of Dr. Cartwright, Mr. Thomas Johnson,
Horrocks, and others, who adapted the loom to be worked
by power. This was practised on a small scale, but did
not come into general use till 1824-5.

The Iron Tbade of this country is one of the most
important, and well entitled to consideration in tracing
our national progress. It would be interesting, if time
permitted, to notice the gradual advances which have been
made during successive ages in the methods of reducing

208 FBOORESS OF ENGINEEBIKG.

the ores. The bloomery or open hearth was probably at
first employed^ the crude product being made malleable
under the hammer. This simple process has been in use
for thousands of years, and is still practised in Africa^
Asia, and even in Spain, wherever the rich specular ores
are found. At what period the bloomery gave place to
the blast furnace it is impossible to determine : but we
find that the process of smelting by the latter had arrived
at considerable perfection in the seventeenth century, and
castings made antecedent to that date are still preserved :
at that time and up to 1740, charcoal was the only fuel
employed in smelting, and the consumption of wood for
this purpose so threatened the destruction of the forests
that prohibitions were issued, and the production of the
furnaces reduced from 180,000 to 17,350 tons per annum.
The introduction of pit coal for smelting, however, changed
entirely the aspects of the iron trade, and from that time
it has steadily progressed to its present enormous rate of
production.

In 1783-4 Mr. Cort, of Gosport, introduced the now
universal processes of puddling and rolling in the manu-
facture of wrought from cast-iron. When mentioning his
, name I cannot refrain from adverting to the gross neglect
to which some of the greatest benefactors of mankind
seem to be doomed, as their only reward for discoveries
which have raised their country to a degree of opulence
hitherto unknown in the annals of history. Cort, the
pioneer of the iron trade, is one of the latest and most
flagrant examples of this want of sympathy on the part
of a highly favoured nation.

The following returns illustrate better than any com-
ments the steady increase of the iron trade : —

JOSIAH WEDGEWOOD.

209

Total quantity smelted in

>»

»>

1740
1788
1796
1820
1827
1854

Tons.
17,350

68,300

124,879

400,000

690,000

3,069,874

At the present time the annual produce cannot be less
than 3,200,000 tons.

Such has been the advance of one of the most important
branches of industry, the support of almost all other trades,
and one which united to coal has afforded this country
treasures more valuahle than a thousand Galifomias.

In closing this part of my subject, I must not omit to
notice Mr. Neilson's application of the hot-blast and the
facilities which it has afforded for the reduction of the
ores and the greatly increased production of the furnace.
Our iron trade has permanently taken a position which,
above all other countries, is distinguished for the skill,
economy, and magnitude with which its operations are
carried on ; and we have reason to be grateful to an All-
wise Providence, for having entombed in the bosom of
our little island such immense and inexhaustible treasures^
for the use of its inhabitants and the glory of its name in
every part of the globe. Without the advantages of coal
and iron, which we possess in such abundance, this country
would never have become the cradle of inventive genius
nor the workshop of the world.

Another benefactor to his country was found in Josiah
"Wedgewood, the founder of the porcelain or Staffordshire
ware manufacture, so well known for its cheapness and
beauty in every part of the globe. To the son of a poor
potter at Burslem we are indebted for an entirely new
branch of industry, and the many benefits we have derived
in our domestic homes from the use of Wedgewood's
pottery can only be appreciated by recollections which

210 PROGRESS OF ENGINEERING.

carry us back to the days of pewter plates and trenchers.
Before Wedgewood's time the earthenware produced in
this country was of the coarsest and meanest description^
and the quantity produced, even bad as it was, totally un-
equal to the demand. In this state of the manufacture
we were dependent upon Holland and other countries for
our supply, until the genius of Wedgewood effected a com-
plete change in the character of the trade, and thus in-
duced not only an ample supply for home consumption,
but a large and growing export into the bargain.

It might be interesting to trace the early career, and
enumerate the troubles and difficulties he had to encounter
in his experiments on earths containing silica: his pro-
cess of calcination, and his process of vitrifaction in pro-
ducing a transparent glass, effected a complete revolution
in the manufacture, and ultimately produced those splendid
specimens of stone and earthenware which, through his
skill, industry, and that of the late Mr. Minton, have
raised the manufacture of English porcelain to its present
high state of perfection.

Other branches of manufacturing industry have ad-
vanced at a similar rate, and I might instance the im-
provements which have taken place in the machinery
for spinning and weaving our woollen, silk, and linen
fabrics, many of which had their origin in the latter part
of the last century; and the real source of which is to
be found in the various inventions employed in the
manufacture of cotton ; to these improvements, however,
I cannot now advert, and I must leave for another even-
ing the consideration of the further development of these
branches of industry which have left their impress upon
the face of the country and on the character of the present
generation of men.

211

LECTURE IV.

ON THE PROGBESS OF CIVIL AND MECHANICAL ENGI-
NEEUING DURING THE PRESENT CENTURY.

In taking up again the subject of the progress of Civil
and Mechanical Engineerings I must be permitted to ex-
plain that a number of the distinguished men who con-
tributed to its advancement in the eighteenth century,
continued at the head of their profession during the first
twenty to thirty years of the nineteenth. Rennie, Telford
and Watt were still living when Bramah^, Brunei, Maudslay
and Donkin rose to a high position in their respective pro-
fessions. For nearly forty years between 1790 and
1830, this phalanx of engineering talent had the field to
themselves, and scarcely any work of importance was
.accomplished without one or other of them having been
consulted.

I well remember that in the early part of my own
career, when I first entered London, forty-seven years
ago, a young man from the country had no chance what-
ever of success, in consequence of the trade guilds and
unions. For myself, I had no difficulty in finding em-
ployment, as it was granted me at once by Mr. Rennie :
but before I could commence work, I had to run the
gauntlet of the trade societies ; and after dancing attend-
ance for nearly six weeks, with very little money in my
pocket, and having to ** box-Harry " all the time, I was
ultimately declared illegitimate, and sent adrift to seek my

212 PBOGBESS OF ENGINEEBING.

fortune elsewhere. There were then three millwright
societies in London — one called the old society^ another
the new society, and a third the independent society.
These societies were not founded for the protection of the
trade^ but for the maintenance of high wages, and for the
exclusion of all those who could not assert their claims to
work in London and other corporate towns. Laws of a
most arbitrary character were enforced, and they were
governed by cliques of self-appointed officers, who never
failed to take care of their own interests. It is true that
in those days mechanical science was at a comparatively low
ebb. Millwrights and mining engineers were in those
days the only men calculated to execute a sound piece
of mechanical work ; there were no mechanical engineers,
and most of the steam-engines, pumps, mills, and other
similar constructions were executed by that class ; and it
is only doing them justice to say, that throughout the
whole of the three kingdoms, they were the only men on
whom the country could rely for the efficient discharge of
these important duties.

In those days a good millwright was a man of large
resources ; he was generally well educated, and could draw
out his own designs and work at the lathe; he had a
knowledge of mill machinery^ pumps, and cranes, and
could turn his hand to the bench or the forge with equal
adroitness and facility. If hard pressed, as was frequently
the case in country places far from towns, he could devise
for himself expedients which enabled him to meet special
requirements, and to complete his work without assist*
ance. This was the class of men with whom I associated in
early life — proud of their calling, fertile in resources, and
aware of their value in a country where the industrial
arts were rapidly developing. It was then that the mill-
wright in his character of ** jack-of-all-trades " was in his
element ; all the great works of the country connected with

TBAJOES' UNIONS. 213

practical mechanics were entrusted to his skill ; and not*
withstanding the intemperate habits of the period which
too frequently trenched upon his time and his healthy he
seldom failed in the duties he had to perform. It was no
wonder^ therefore, that at the commencement of the new
movements in practical science, occasioned by the inven-
tions of Watt and Arkwright, the millwright should assume
a position of importance. Under these circumstances, to
use the expression of the shops, the men were masters, all
having the same wages — seven shillings a day and their
drink, and it was then, or some time before, that the
societies of which I have spoken were formed, and con-
tinued for years to exercise an unlimited sway over the
talent and industry of the metropolis and other corporate
towns. I am sorry to say that the same intolerant and
exclusive system is still in operation in particular trades,
and it is much to be regretted that intelligent workmen
cannot perceive its destructive influence on the comifort
and prosperity of themselves and their families. It is
in vain to point out the dangers arising from the con-
version of benefit societies into trades' unions with paid
secretaries, treasurers, &c. And the designs which these
functionaries have upon the -subscriptions are forgotten
or neglected until the whole of the accumulated capital
is involved in fruitless contests, and the men are left,
without money and without employment, to bewail their
imprudence in a state of helpless destitution. A^few
years ago there was a striking illustration of its injurious
influeiice in the case of the " Amalgamated Engineers," and
according to the Times of December last (1858), things
are not much better in some cases at the present time.
*^ The Letter Press Printers' Union affixes a stigma to all
operatives who choose to take care of themselves, and
venture to manage their own concerns. A printer not

belonging to the Union is called a ^ rat,' and Union men

p 3

214 PBOCBESS OF ENGINEERING.

positively refuse to work in his company.'^ This is no
new case, as I have found from experience both as a
journeyman and as a master ; and I leave it to the good
sense of this meeting to decide whether it is just, whether
it is for the benefit of either the operatives or the pub-
lic, that the energies of individuals should be thus crippled,
and the exercise of their profession denied them from
the illegal exercise of control by men who create, for
their own selfish ends, only misery and discontent in the
families whose interests they profess to represent. I
mention these cases to show the injurious working of a
system of protection and uniform pay, and the jealousy
and exclusiveness of the trade guilds in maintaining the
institutions of the fine old times of good Queen Bess*,
when you had to be a seven years' apprentice or the
eldest son of a journeyman or freeman of the city to
which you belonged, before you were permitted to work.
Such restrictions as these threw a blight over the bright
opening days of a new era, and retarded our mechanical
progress as much, if not more, than the expensive and
sanguinary war in which we were at that time engaged.
At the Peace of 1815 many of these evils were removed,
and in giving to the nation rest it gave time for inquiry
into abuses, which led more or less to the extinction of the
exclusive system, and left open to all classes a fair field and
no favour in the race of national progress.

Probably no class has derived greater benefit from these
changes than that to which I belong; it has now full
scope, and I have to congratulate you that we live in an
age and country in which every facility is afforded for im-
provement, and where the inventive faculties are appre-
ciated and fostered in every department of science and art.

* It was considered in those days that an apprentice coald not learn his
trade or handicraH; in less time than seven years, and hence the privileges
granted to corporate towns.

JOHK RENNIE. 216

About tie year 1785, John Rennie (who served his
apprenticeship as a millwright with Mr.' Andrew Meikle,
of Phantassia, near Edinburgh, the inventor of the thrash-
ing machine,) was employed by Boulton and Watt, in the
erection of the Albion Mills; and in the construction of
Jhe mill work and machinery of that establishment the pro^
prietors received most able assistance from him. I believe
he was the first to introduce cast-iron in improved forms and
for purposes for which wood alone had previously been em-
ployed, and displayed considerable skill in the adaptation
of metal to such purposes. His water-wheels, mills,
&c., were considered models of perfection, and the arrange-
ment of the cistern, shuttle, &c., of the former was so
nicely adjusted as to save every drop of water and turn it
to account. The construction of this machinery led Mr.
Kennie to the study of hydraulics and hydrodynamics, in
which, from his native resources, he soon became celebrated
as the worthy successor of Smeaton. As a millwright
Mr. Bennie wad one of the most successful in the profes-
sion, and his works yet remain in the flour-miUs at
"Wandsworth, the rolling and triturating mills of the mint ;
and many others bear testimony to the accuracy and
skill of the constructor. As an architect and engineer
also, Mr. Kennie stands quite pre-eminent; and it is
almost impossible to enumerate the great works which
emanated from his hands. As a bold and ingenious
engineering work, we may mention Southwark Bridge, of
three arches of cast-iron, which for solidity and span has
not an equal even at the present time* For architectural
beauty and harmony of curvature, no structure surpasses
"Waterloo Bridge ; and if to these we add the bridges of
Eelso, Musselborough, Boston, New Galloway, and others,
we shall find that as a bridge builder Mr. Rennie was
without a rival, with the exception only of Telford, during
the whole of his useful career. Rennie, moreover, was largely

F 4

216 FB06BE8S OF ENGINEEBIN0.

engaged in the construction of canals and harbours, and
his opinion and assistance were sought for from all
quarters. During the greater part of his career a rage
for canals prevailed, not dissimilar to that at a later period
for railways. The Lancaster, Kochdale, Portsmouth,
Birmingham, Grant Western and Crinan canals ; th^
Plymouth breakwater, and the docks at Hull, Greenock,
Leith, Liverpool, Portsmouth, Chatham, and Sheemess,
bear witness to Kennie's skill as a civil engineer ; and so
multifarious were his resources, so persevering his industry
and sound his judgment, that no one will be disposed to
deny that he worthily earned a niche in the temple of
fame. It is recorded of him that his conversation was
always instructive and amusing ; he possessed a rich fund
of anecdote, and like his old friend, James Watt, would
tell a Scotch story with a relish and humour highly
characteristic.

Next to Bennie, and equally renowned as a civil en-
gineer, was Telford, the son of a shepherd, bom in 1757,
in the pastoral district of Dumfries and Boxburgh, and
brought up to the trade of a stone-mason. He received
the rudiments of his education in the parish school of the
village of Westerkirk during the winter time, and in
summer he assisted his uncle as a shepherd. Whilst
thus occupied he procured some books from his village
friends, and by these means employed his time to good
purpose, in early life he was a poet, and during the
time he was a stone-mason, and even for some time after
he left Scotland, he cultivated the muses and published
at Shrewsbury a poem, entitled ** Eskdale," descriptive of
the scenes of his early life : —

" Here lofty hills in varied prospect rise,
Whose airj snmmits mingle with the skies,
Boand whose green brows and by the aged thorn,
The early shepherd seeks his flock at morn ;

TELFORD. 217

Or on the sanny side, at noontide laid,
Sees bis white charge in gay profusion spread,
While round the knowe, beneath the inspiring sun,
His bounding lambs their playful races run."

He also wrote and published an address to Robert
Burns in the Scottish dialect; but these flights of the
imagination ultimately gave way to the more engrossing
duties of a profession^ upon the success of which his fame
now rests.

Telford^ though an older man than Kennie by four
years^ did not come into notice as an engineer until the
latter had attained to considerable distinction. Towards
1792-3^ we find him practising as an architect and surveyor
in the county of Salop, and there he commenced his
career as a bridge builder and engineer. His first bridge
worthy of notice was that over the Severn at Mountford,
near Shrewsbury; it consisted of three elliptical stone
arches, one of fifty-eight feet and two of fifty-five feet
span. His next bridge was of iron, and crossed the
Severn at Buildwas ; it was of 130 feet span, being the
segment of a large circle, which gave a grace and beauty
to the structure, not to be found in the semi-circular
bridges previously constructed. From this time iron be-
came more general in the construction of bridges, and its
use enabled the builder to reduce the number of piers,
and thus to give greater facilities for the passage of floods
and the free navigation of rivers. Telford showed great
merit in his improvements of these structures, in the
various elegant bridges which he subsequently erected.

Amongst the boldest designs of this kind were the
colossal cast-Iron bridge proposed to be erected over the
Thames, and the wire bridge of one span of 1000 feet,
and two side spans of 500 feet, designed to cross the
Mersey at Runcorn Gap. Neither of these were executed,
but Telford has left splendid monuments of his skill in the

218 PBOGBESS OF ENGINEERING.

Menu and Conway Suspension Bridges, with many others,
both of stone and iron, which establish his position as one
of the leading engineers of his time.

In the construction and improvement of canals and har«
hours, Mr. Telford was equally successful ; and we may
instance the Gotha Canal in Sweden, the Caledonian Canal,
and several others of nearly equal importance at Birming-
ham, Glasgow, Paisley, &c., as examples of his skill. To
these works must be added his improvements of the har-
bours of Aberdeen, Dover, and the Clyde, and the new
outfall of the North Level Drainage. Telford's name is
also associated with some very important works of road-
making, and in this department of engineering he is with-
out a rival. Before the introduction of railways the
means of transit were brought to a high state of perfection
by the improvements of the turnpike roads ; and the new
system of road-making, first introduced by Mr. M*Adam,
was extensively carried out upon sound principles of con-
struction by Telford. Most of us will remember the per-
fection of stage-coach transit, antecedent to 1830, and the
bustle and activity created in every little town along the
great thoroughfares of the kingdom, by the arrival and de-
parture of the mail and stage coaches. The admirable
working of this system, which created so much astonish-
ment in the minds of foreigners, owed much of its success
to the sound principles of road-making, solid foundations,
smooth surfaces, and effective drainage, carried out by
Telford.*

In closing this sketch, I must not omit to notice the many
excellent qualities of Telford's private character, and of
these I can speak from personal acquaintance. He united

* The smooth and heantiful roads in the Highlands of Scotland were
executed by the late Mr. Mitchell and his son, the present intelligent
engineer, under the direction of Mr. Telford.

6TEAM KAVIG ATIOlrf, 219

to a mind endowed with philosophical acquirements great
benevolence and goodness of heart, which rendered him ac-
cessible to all who required his assistance ; and the young
aspirant after knowledge was sure to find an encouraging
patron and noble example in Thomas Telford; He was
succeeded in his professional career by Mr. James Walker,
whose works in harbours, docks, &c., are so well known.

St£AM Navigation, of which we have not yet spoken^
is of much greater antiquity than most persons suppose.
It is said that Dr. Papin suggested the use of steam
to work paddle-wheels as early as 1690, and that he
actually propelled a vessel on the Fuldaby one of Savery's
Engines in 1707. How far this statement is entitled to
credit I am not prepared to say ; but Jonathan Hulls took
out a patent in 1736 for a boat with paddle-wheels over
the stern ; and the Compte D'Auxeron and M. Perrier are
stated to have made experiments upon a paddle-wheel
steamboat in 1774 ; but, like most other premature inven-
tions, these remained unproductive for many years.

In 1788, Mr. Miller, of Dalswinton, assisted by Mr.
Taylor, then in the capacity of tutor in his family, made
the first certainly successful trial of a steam-boat worked
by an engine and paddle-wheel. The boat was a twin
boat with the wheel in the middle, and driven by an
engine with a cylinder of four inches diameter. This
engine is, I believe, in the Government Museum at Ken-
sington Gore. The following is the account of the expe-
riment which appeared in the newspapers at the time : —
"On the 14th instant a boat was put in motion by a
steam-engine upon Mr. Miller's piece of water at Dal-
swinton. That gentleman's improvements in naval affairs
are well known to the public. For some time past his
attention has been turned to the application of the steam-
engine to the purposes of navigation. He has now accom-
plished, and evidently shown to the world, the practica-

220 FBOGRESS OF ENGIKEEBIKG.

bilitj of this by executing it upon a small scale. A vessel
twenty-five feet long and seven feet broad, was on the
above date driven with two wheels by a small engine. It
answered Mr. Miller's expectations fully. The engine
used is Mr, Symington's new patent engine."*

This experiment led to a second essay by the same
parties upon a larger scale. In the autumn of 1789 a
boat was fitted up upon the Forth and Clyde Canal^ and
engines with 18-inch cylinders placed in it; on trial a
speed of six to seven miles an hour was easily obtained.
From some unaccountable cause Mr. Miller neglected to
patent his invention^ after having established at very great
cost, the practicability of employing steam as a motive
power in the propulsion of vessels.

The next most important experiment upon this subject
was made in 1801-2, when Lord Dundas, of Kerse, with
the assistance of Symington, built a boat for towing vessels
upon the Forth and Clyde Canal. This vessel, named
the Charlotte Dundas, obtained, with an engine of twenty-
two inches cylinder and four feet stroke, an uninterrupted
speed of seven miles an hour.

" In this vessel (fig. 34), there was an engine with the
steam acting on each side of the piston, working a con-
necting rod and crank, and the union of the crank to the
axis of Miller's improved paddle-wheel. Thus had Sym-
ington the undoubted merit of having combined together
for the first time those improvements which constitute the
present system of steam navigation."!

The early experiments of Miller, Taylor, and Symington,
of this country, had scarcely become known at the time
of the realisation of Watt's great discovery of the double
action condensing engine, when the enterprising Ameri-
cans began to attempt the application of steam to the pro-

♦ Bennet Woodcroft's History of Steam Navigation, p. 36.
t Bennet Woodcroft, p. 54.

EABLT EXPEBIMENTS. 221

pulsioQ of vessels. Finch, Rumsey, and Stevens were
early in the field, but it was reserved for Fulton to give
the crowning effort to all previous experiments by the
introduction of his first boat on the Hudson in 1807-8,
where it plied between New Tork and Albany as a regu-
lar packet-boat. From that time the Hudson has been
the scene of most of the improvements in steam navigation
that have taken place on the American waters.

From the period of these experiments down to the
present time a succession of improvements have led to

Fig. 31.

the employment of steam-vessels to so great an extent
as to change the relations of all countries, and to esta-
blish a new era in the history of navigation. The paddle-
wheels of steamers have undergone several modifications,
such, for instance, as Morgan's and Galloway's patent
wheels, with a vertical rise and dip of the float boards ;
but the greatest advance which has yet been made
ia the introduction of the screw-propeller. There are
many claimants for this invenljon, but none are better

222 PROGRESS OF ENGINEERING.

entitled to the credit of practically introducing it than
Captain Smith and my friend, Mr. Bennet Woodcroft
As early as 1830 I witnessed the performance of Mn
Woodcroft's working model, with a screw on each side of
the vessel, and since then he has introduced the variable
pitch, and improvements for connecting and detaching the
screw when the vessel is under canvass. Captain J. P.
Smith, however, was the first to apply the screw in a
practical form, and I well remember the trials of the
"Archimedes" on the Thames some twenty years ago,
the results of which took the nautical world by surprise,
and created no small degree of alarm in the minds of the
advocates of non-progression and let^well-alone. Now
the screw has become one of the most important instru-
ments of propulsion both in vessels of war, where the pro-
tection of the implements of motion from injury by cannon
shot is absolutely requisite, and also as a principal or
auxiliary in our mercantile marine.

What great advantages we have received from this ex-
tension of steam power I How much the danger to life
and property has been diminished ! What certainty and
despatch have been secured in spite of wind and tide, in
the conveyance of intelligence, the transport of troops,
and the interchange of natural and manufactured products I
But looking onwards from these realised benefits, we must
admit that the same power which moves vessels of great
size with so much celerity, and gives so many advantages
to the country in its commercial relations, is nevertheless
a source of danger as well as security, in the facilities it
-affords for sudden incursions by hostile armaments, at
various points along our unprotected coasts. The exten*
sive use of steam in the Navy will necessitate an entirely
new system of tactics, and the sooner the Government is
alive to the existence of the danger from this source which
our own improvements in marine propulsion have created.

lEON SHIPBUILDING, 223

the sooner we shall be prepared to repel aggression fron^
whatever quarter we may be assailed. It is well known
that every change in our habits and conditions of life is
sure to be resisted "tooth and nail" by all those who
wish to maintain the dignified position of ** as you were."
This standing at ease is out of fashion now-a-days, and
we must either move on, or be left a stranded wreck in
the tide of progress. I am most desirous to impress these
facts upon you, and upon the authorities of the Admiralty,
where so much must be done in initiating a new system
of naval tactics before we can be prepared for the exi-
gencies of a maritime war, possibly not far distant, and
which, whenever it arrives, will have to be maintained by
the agency of steam. Steam rams may or may not come
into use, but it is certain that increased steam power and
increased speed in the Navy may give to the nation that
ascendency in maritime affairs which more than anything
else is its greatest security considered in its relations with
other countries. I ani, therefore, most anxious to see our
own Navy foremost in power and perfect in discipline, so
that England may long continue in pride and glory the
mistress of the seas.

Iron Shipbuilding. — This is a subject with which I
have been intimately connected for many years, and to the
advance of which I have had the honour of contributing. I
was the first to commence iron shipbuilding in London, and,
I believe, was the second to send an iron vessel to sea.
From 1829-30 to 1848 I built upwards of 120 iron vessels,
some of them upwards of 2000 tons burden, and nine of
which were built in sections at Manchester, and the re-
mainder on the banks of the Thames at Millwall. If time
permitted I could give you the whole history of this
important branch of industry, and show from what small
beginnings one of our largest branches of industry has
sprung. Suflice it to observe that in 1829-30 Mr. Hous-

224 PB0GBE8S OF ENGINEERING.

ton, of Johnstone, near Paisley, launched a light glg-boat
on the Ardrossan Canal for the purpose of ascertaining
the speed at which it could be towed by horses with three
or four persons on board. To the surprise of Mr. Hous-
ton and the other gentlemen present it was found that
the force of traction, or labour the horses had to perform in
towing a light boat of this description, was much greater at
a velocity of six or seven miles an hour than at nine miles
an hour. This anomaly in the trials was puzzling in the
extreme, and it was in this stage of the experiments that
I was requested by the Council of the Forth and Clyde
Canal to visit Scotland and institute a series of experi*
ments with light boats in order to determine the law of
traction, and to clear up the anomalies of Mr. Houston's
experiments.

The Forth and Clyde experiments commenced in the
spring of 1830, first with wooden, and ultimately with
light iron boats ; and these experiments led to the con-
struction of iron vessels upon a large scale and on an
entirely new principle of construction, with angle iron
ribs and wrought iron sheathing plates. With the ex-
ception of these iron canal boats the first iron vessel was
made in 1822, and was navigated from this country to
Havre de Grace by Admiral, then Captain, Napier, with
the intention of employing it upon the Seine. The next
iron vessel was built by myself, at Manchester, and
another (the Alburka) by Laird, both of which were com-
pleted, and went to sea in 1831. From that time to the
present iron vessels have been built of all sizes, from
the smallest wherry up to the Leviathan of the Great
Eastern Navigation Company.

The experiments on the Forth and Clyde Canal occupied
a series of years, and no less than five experimental
vessels were made at a cost of several thousand pounds ;
the results not only elucidated the phenomena of diminished

IRON HOUSES. 225

traction at high velocities, but led to a new construction of
iron Vessels, and other structures, of which wrought-iron
formed the whole or the principal material. These
experiments, however, did not accomplish the ardent
wishes of the proj)rietors of canals, who at that time
were alarmed at the progress of railways, in consequence
of the competition at Kainhill, in the same year, for the
best locomotive engine. .It was then railways versus
canals; and although in the experiments we obtained a
velocity as high as fourteen miles an hour with a light
boat drawn by horsesj we never could obtain more than
seven and a half to eight miles by steam.

Iron Houses. — Iron as a building material is not
confined to ship-building alone ; it is employed in almost
every other department of useful art, and is now largely
applied to the construction of houses. When cast and
w^rought-iron are united in these constructions, they form
some of the most convenient and beautiful combinations
possible. All the forms of highly decorative architecture,
cornices, mouldings, &C.5 can be produced in castings from
pattern models; and these united together with plates
either corrugated or plain, and securely riveted to a frame-
work of angle or T iron, give to a house of this kind
erected upon a basement of stone or brick the charac-
teristics of a cheap and handsome edifice* Warehouses,
shops and private residences are now built in this way,
and I might instance the large edifices recently erected in
New York, Glasgow, and other places, where the whole of
the street fagade is constructed of iron, and that in a style
of architecture perfectly symmetrical and in harmony with
the finest stone buildings in either city.

As a material for street architecture, it is admirably
adapted, from its powers of repetition and security from
fire ; and I ^m one of those who have great faith in iron
walls and iron beams, and although I have both spoken

226 PROGRESS OF ENGINEERING.

and written on tlie subject, I cannot too forcibly recom-
mend It to public attention. It is now twenty years since I
constructed an iron house with the machinery of a corn mill
for Halil Pasha, then Seraskier (commander-in-chief) of
the Turkish army at Constantinople, I believe it was the
first iron house built in this country, and was constructed
at the works at Mill wall, London, in 1839.

Iron Bridges form another class of constructions in
which, of late years, iron has been most extensively em-
ployed, both in its cast and malleable conditions* Iron is
employed for bridges on three principles, the suspension
chain, the horizontal beam or girder, and the arch* The
earlier bridges were of cast-iron, and were erected in the
form of large semicircular arches, sustained by heavy
abutments, formed of masonry. The introduction of cast-
iron in this form dates from a period not more remote than
1779, when Mr. Pritchard, with the aid of Messrs. Darley
and Reynolds, constructed a bridge over the Severn at
Colebrookdale, and even in this first attempt it indicated
its superiority over stone for large spans. From that time
to the present a very large number of cast-iron arched
bridges have been erected, both |br railway purposes and
for ordinary road traflfic, but none of them have exceeded
250 feet span.

The introduotion of railways created a demand for a
great number of bridges of small span for crossing roadways
and canals, in cases where it was requisite that the depth
of the bridge* should be as small as possible. For spans of
forty to fifty feet, this demand has been admirably met by
the introduction of cast-iron beams, with a perfectly hori-
zontal soffit, but for larger spans they are objectionable and
dangerous. The best form for larger spans, where cast-
iron is required to be used, is the flat arch with a versed
sine of about l-20th the length of the chord. This de-
scription of girder partakes of the properties of the beam as

IRON BBIDGES. 227

well as the arch; it does not depend entirely upon voussoirs,
as an arch of equilibrium, being partly retained in form by
the unyielding nature of the abutments resisting the
thrust of the arch ; and from its connection at the joints
by bolts, it becomes a beam with a large camber, support-
ing the load by its resistance to compression and extension,
along the top an3 bottom flanches.

The true development of girder bridges was not, how-
ever, attained, until the experiments in connection with
the erection of the Conway and Britannia tubular bridges,
determined the true forms and proportions in which
wrought-iron should be distributed to resist the enormous
strains to which bridges of wide span are subjected.
Wrought-iron as a material for bridges is free from the
objections which attach to cast-iron; it is uniform in
strength and texture, of well-ascertained properties, en-
tirely free from those irregular strains to which cast-iron is
subject from unequal contraction in cooling ; and, more-
over, its tensile and compressive strengths when arranged
in suitable forms do not bear so great a disproportion to
each other as is the case with cast-iron. Hence the intro-
duction of wrought-iron for railway and other structures
in which certainty of construction and security from danger
are required, has proved to be one of the most important
eras in the history of bridges.

- It will not be necessary to -trace the origin and course of
the experiments which were instituted to determine the
proper form and dimensions of the tubular bridges which
cross the Conway and the Menai Straits. Suffice it to
observe, that in the construction of the Chester and Holy-
head railway, it was found necessary, in order to comply
with the demands of the Admiralty (who watched over
the interests of the navigation of the Straits), to erect a
bridge of colossal dimension?, having four spans, and leav-
ing a clear opening on each side of the centre pier of 460

228 PBOGRESS OF ENGINEERING.

feet, with an elevation of 100 feet from the level of high
water to the bottom of the bridge.

This could not have been accomplished by the ordinary-
applications of iron, such as cast-iron arches or chain
bridges ; the former not giving sufficient height above the
water-level, and the latter from their flexibility being un-
suited for the support of railway trains. It was ultimately
conceived that huge wrought-iron elliptical tubes, supported
by chains, through which the trains should pass, might
meet the demands of the Admiralty. But before this con-
ception was adopted, a laborious series of experiments
was instituted, which pointed out the defects of the
elliptical tube, gave the true principle on which such
a structure should be designed, determined the for-
mulas for calculating its strength and proportioning its
parts, and thus established an entirely new system of con-
struction. The Britannia Bridge was then erected, and
with its companion at Conway remains with hundreds of
others composed of the same material and upon the same
principle of construction, memorials of the accuracy of the
investigations which led to the introduction of wrought-
iron in this and other systems of adaptation. The total
length of each tube of the Britannia Bridge is 1524 feet;
height in the middle, 33 feet; and width, 14 feet 8 inches.
The total weight of iron amounts to the enormous quantity
of 10,570 tons. The Conway Bridge is of smaller dimen-
sions, consisting of one span of 400 feet, prossed by two
tubes, each 424 feet long, 25 feet 6 inches in height at
the middle, and 14 feet 8 inches wide. The weight of
iron amounts to 2892 tons.

Since the erection of these bridges wrought-iron has
been extensively employed for girder bridges of all spans
up to 500 feet, and it is capable of being extended if
necessary to spans of 1000 feet.

Prime Movers. — From 1784 to 1815, the cotton
trade, with some fluctuations, made considerable progress ;

WATER-WHEELS.. 229

but the steam-engine was comparatively little appreciated
or applied. In the earlier stages of manufacturing in-
dustry, the mills were erected on streams with waterfalls
of sufficient power to turn their machinery. Hence the
distribution of the mills over the country — as at Cromford,
Belper, Bakewell, and Darley. At the commencement of
my own career this was the condition of some of the largest
cotton works in the kingdom. At the present time water,
as a motive power, is only of secondary consideration, nine-
teen-twentieths of the mills now in existence being driven
by the steam-engine. I well recollect the skill, beauty,
and solidity with which the water-wheels were constructed
when water was generally the motive power. The best of
these wheels were made entirely of iron, on the principle of
suspension, the arms not exceeding two or two and a quarter
inches in diameter, and the power being taken off from
the periphery by a pinion on the loaded side of the wheeL

Mr. T. C. Hewes is justly entitled to the merit of these
improvements, and was assisted by the late Mr. Strutt,
of Belper. The most important of the recent improve-
ments of the water-wheel are, however, the ventilation of
the buckets and the use of cotters in the place of nuts and
screws for fixing the arms and braces to the centre flanges
of the wheel.

Fig. 35 represents a large water-wheel of iron, of the best

modern construction, and erected at Gefle, by W. Fairbairn

and Sons, near Stockholm, in Sweden. This wheel is 40

feet in diameter, and 20 feet broad, or 18 feet between the

shrouding plates. It is supported on the large cast-iron

axis, a a, by means of the small wrought-iron arms, c c,

and braces b i, on which the wheel is in fact hung or

suspended. The arms are attached to the shrouding

plates 9 «, and at the other end to the main centre, to

which they are fixed by gibs and cotters. The braces are

similarly attached diagonally between the main centre and

230 PROGRESS OF ENGINEERIKG.

the middle ring of cast-iron. Around tlie periphery of
the wheel is fixed an internal spur-wheel, d, cast in seg-
ments, into which gears the pinion e, so as to aSbrd
the highest yelocitir direct from the water-wheel; this

again is further increased by the spur-wheel f and
pinion g, and bevel wheels k and h, which transmit the
power to the upright shaft i of the mill.

THE STEAM ENGINE. 231

There is therefore (1,) the water-wheel segment, rf, with
324 teeth of 4^ inch pitch, and 14 inches width, giving 2
revolutions per minute, geared into, —

(2,) Pinion e^ 6 feet 1 inch diameter, giving 12*3 revo-
lutions of cross shaft

(3.) Spur-wheel/, 20 feet diameter, geared into pinion
.^, 5 feet 6 inches diameter, giving 43 revolutions per minute
to second cross shaft.

(4.) Bevel- wheel A, 7 feet 8 inches, geared into bevel
wheel A, 4 feet 1^ inches, giving 80 revolutions of upright
shaft i of mill.

The power of this wheel Is equivalent to 150 horses.

Figs. 36 and 37 illustrate the construction and details of
two pairs of condensing beam engines of 400 total nominal
horses power, employed in driving the machinery for pre-
paring spinning and weaving alpaca fabrics in the exten-
sive mills of Titus Salt, Esq., of Bradford. They may
serve as types of the present development of steam prime
movers. These engines are arranged in two large engine-
houses on either side of the front entrance to the mill
buildings, and they are supplied with steam from ten
boilers placed in a boiler-house beneath the surface of the
ground, and a short distance in front of the mills. Fig. 36
shows a side elevation of one of these engines, giving a
general view of the arrangement of the parts, and fig. 37
a cross section. The power generated in the cylinder e,
and transmitted through the working beam b b to the
large fly-wheel m?, 24 feet in diameter, is taken direct
from its circumference by the pinions p /?, which give it
off at the required velocity to the shafting of the mill.
This arrangement has become very general for factory
engines, and is the most effective and economical plan for
generating at once the high speed which they require.

The valves are of a peculiar construction, being a modi-^
fication of the double heat or equilibrium valve invented

232 PROGtiESS OF EKaiNE£Ri:TG.

by Mr. Hornblower, and they have the merits of afibrdinf;
any required amouDt of expiinsion, with a rapid cat off,
and absence of wire drawing, and a fully open passage to
the condenaer during the whole of the atroke. In ordinary
Tvorking these engines give 900 actual horses power,

Fip, 3S.

although they are capable of considerably more. They
burn 16 tons of slack coal per day.

The following dimensions are given that they may be
compared with the engines selected for illustration in my
former lecture, and the progress made in mcchaDicol

THE STEAM ENGINE.

Ecience eince the time indicated by the n
ments in practical a

B early develop-

Dinmeter of cylinder , , . 50 inchea.

Stroke 7 f«et.

Length of beam . , . .31 feet T inc

Diameter of fly wheel . . . 2* feel.

Treeeaie of steam ia boiler . . 20 lbs, per e

Nominal poirer of each engine . I CN) horses.

Indicated or working power, at

33,000 lb», raised one foot high

• inamiante, or the actual power

given oat by each engine, in

equivalent to . . . . 300 horses.

Kb. s7.

234

PROGRESS OF ENGINEERING.

MiLLWORK. — In the machinery of transmission as
great improvements have been made as in any other
department of practical science, and I have to attribute
my own success in life to the changes which it has been
my privilege to introduce into this class of machinery.
When I first entered Manchester the mills were driven
by large square oast-iron shafts (fig. 38), on which huge
wooden drums revolved at the rate of about forty revolu-
tions per minute ; and the couplings Avere so badly fitted
that you might hear them croaking at some distance
from the mills. Now, the wheels and shafts (fig. 39) are

Fig. 38.

Fig. 39.

executed with an almost mathematical precision, and instead
of huge drums four or five feet in diameter, revolving
thirty or forty times a minute, we have small light
turned pulleys, keyed upon polished iron shafts, revolv-
ing at 120 to 200 times per minute. In figs. 38 and 39
the change is apparent, as both shafts are calculated to
perform the same amount of work, notwithstanding their
apparent difference in size and strength. The introduction
of lighter shafting led also to the simplification of the
hangers and fixings by which it is supported, and to the

MILLWOEK. 235

•
introduction of the half-lap coupling, so well known to mill-
wrights and engineers. The fly-wheel of the engine was
also converted into a first motion by the formation of teeth
on the periphery (w, figa. 36 and 37), which resulted in a
considerable saving of cost and power. This eystem was
at firtft condemned by some of our leading engineers, and
it was with diificulty that I overcame the opposition they
created; indeed it'was not until a wheel of thirty tons
weight for a pair of engines of lOO-horse power each was
erected, that the prognostications of failure entirely ceased.
The principle has now become general wherever steam is
employed as a motive power in mills.

Pig. 40.

23S FB0GRE8S 07 EK6INEEBING.

Corn Mills. — Figure 40 is a sketch of a corn mill
erected in 1730, and dearly illustrates the condition of
millwork and gearing at that time. Figs. 41 and 42 exhibit

the present condition of this important branch of the mill-
wright's art. As in most English mills of the present

CORN MILLS.
Kg. 42. ■

238 PROGRESS OF ENGINEERING.

day, it will be seen that the pairs of stones, twelve in
number (a a a) are arranged in a single line, enclosed in
iron cases, and supported on strong iron framing {b b).
The power required to drive the mill is obtained from a
steam-engine, the fly-wheel of which gears into the
pinion c, and the motion is then distributed on each side
to the stones by the bevel wheels ddd. The wheat, as it
is brought to the mill, is first delivered in its uncleaned
state into the wheat garners ff ff, situated upon the
machine flat. From these it is passed by means of Archi-
medean screw creepers to the wheat screen or smut
machine h, whence it falls Into an elevator through the
spout i, which raises it again to the upper story; it is
thence distributed by another creeper into the clean wheat
garners kkh ; from these it passes by the feed pipes ///,
to the feed hoppers of the stones y, and after being ground
to flour is raised again by a creeper and elevator to the
machine floor, where it passes through the dressing and
bolting machinery. Fig. 42 is a section of a pair of stones
with its driving and feeding apparatus, stone case {a\
rhind (w), bed stone {n\ and running stone (/?). Such a
mill as this will grind 70 to 90 bushels of wheat per hour,
according to the dryness of the grain employed.

Railways. — In tracing a faint outline of the progress
of practical science and industrial art, we have yet to
notice one of the most important improvements that has
ever occurred in ancient or modern times. The railway
system, combined with the locomotive engine, is both a dis«
covery and an invention, and. the introduction of these de-
velopments, contemporaneously with the progress of steam
navigation, has changed the destinies of nations, and
brought the most distant and barbarous races within the
reach of civilisation.

Railways are of comparatively remote origin, having
been in use for upwards of two hundred years, as may be

RAILWAYS. 239

seen from records of the collieries of Northumberland,
dating from the time of Charles the Second. I still re-
tain a distinct recollection of being employed, in 1807,
at the Percy Main Colliery,- in making patterns for
cast-iron fish-bellied rails and these were amongst the
first, if not the first, iron rails introduced as a substitute
for wood. For many years after this cast-iron was em^
ployed, and it was not until the locomotive rendered a
tougher material requisite that wrought-iron was substi-
tuted for cast. The form of section of these rails was at
first defective in the extreme, but they have since been
constructed on sounder principles, and of stronger and
heavier proportions.

Iron roads, however, are of little value without the
locomotive engine, and the latter we owe exclusively to
the marvellous developments of the last forty years.
Imperfect and premature attempts were made to introduce
steam as a motive power for carriages more than a hundred
years ago ; and Mr. Murdock, of Soho, made a working
model of a locomotive-engine at the close of the last
century, which I have myself seen travelling on a
circular railway at the rate of five miles an hour. Mr.
Trevietheck also made a locomotive-engine in 1804,
which was mounted on a carriage with four wheels, and
worked on an iron tramway at Merthyr Tydvil, dragging
waggons loaded with fifteen tons of iron for a distance of
nine miles in rather less than two hours. Mr. Blenkinsop,
however, introduced the first really successful engine at
Leeds in 1812. This engine worked for many years, and
in order to prevent the wheels from slipping, racks were
introduced upon the rails with large hollow cogs, into which
the corresponding teeth on the wheels worked. This
contrivance, however, was soon abandoned, the adhesion
of the wheels to the rails being found sufficient to prevent
slipping.

240 PB0GBE8S OF ENGINEERING.

The success of Blenkinsop's engine induced the coal-
owners of Newcastle to make a similar experiment on
their tramways, with a view of dragging the empty wag-
gons up the inclines in this way. It was in these and
subsequent experiments that George Stephenson first
became known, whose skill and exertions have since so
deservedly earned for him the title of the ** Father of
Railways.'* He was one of the most courageous and per-
severing engineers this country has produced. Endowed
by nature with great powers, although comparatively un-
cultivated and uninstructed, he never lost sight of the
object of his pursuit, and his never tiring energy of cha-
racter carried him successfully through difficulties which
would have crushed more ordinary men. George Stephen-
son was never afraid of work, and by the constant exercise
of a sound judgment, combined with indomitable perse-
verance, he was led to the honourable accomplishment of
the great work he had to perform. Such was his character
when I first worked an engine for him on the Tyne, and •
such was the man when I last parted with him a few
weeks before his death.

Time will not permit me to enter into detail on the pro-
gress of the locomotive engine, in all the changes and trans-
formations through which it has passed. Suffice it to
observe, that Mr. Jonathan Foster, of Wylam, 'near
Newcastle, was among its first improvers; he connected
all the four wheels by spur gear, first dispensing with the
tooth work on the wheels and rails. Stephenson then
altered the positions of the cylinders and wheels, improved
the flues and furnaces of the boiler, and introduced the blast
into the chimney, one of the most important elements
in the success of the locomotive. A long and angry con-
test has been carried on in the journals as to the priority
of the invention of the blast, but I have every reason to
think it belongs to Stephenson, as I have heard him claim

THE BAIKHILL COHFETITION. 241

ita introduction, and have no reason to doubt his veracity)
or that he was quite equal to the task. Mr. Trevithick
19, however, said to have introduced the exhaust or waste
steam pipe into the chimney in 1806, to obviate the noise
occasioned by the steam rushing into the air, and he is re-
ported to have found that a greatly increased draught and
a diminished consumption of smoke and fuel resulted from
this modification.

The trial of locomotives at Rainhill, in 1830, at which I
was present, developed entirely new principles in the actiou
of the steam engine, and indicated by its unexpected results
the high velocities which would follow the employment of

Fig. 43.

steam power upon r^ways, although at that time neither
Mr. Stephenson nor any one else had any adequate con-
ception of the benefits which the extension of railways
has already secured. It was the general belief of tliose

242 PROGRESS OF ENGINEERING.

interested in the trial that a speed of ten or twelve miles
an hour was the utmost that could be obtained^ although
an able writer in the Scotsman had argued some mondis
before that the only limit to speed was the power of the
engine. The blast of waste steam in the chimney, the
introduction of small tubes in the boiler, as suggested by
Mr. Henry Booth, and the enlargement of the furnace,
were the great improvements of the locomotive engine,
and were all exhibited in the *^ Rocket" of George Ste-
phenson. This engine, which is shown in fig. 43, was
the successful competitor at the Rainhill trial. From
1830 to the present time little or no change has been
made in these principles of construction, but great mo-
difications of the arrangement and of the details have been
effected, and with these the locomotive is now one of the
most perfect and effective machines ever constructed.

In my former address I gave an estimate of the total
horse-power of the locomotives of the United Kingdom.
I will now give you some idea of the energy of a single
locomotive engine. When travelling at forty miles an hour,
with a pressure of 90 lbs. per square inch on the piston, it
will be found that a large locomotive exerts a force equiva-
lent to about seven hundred horses ; and these data, so well
calculated to astonish the unreflecting, should make us
proud of the country where such triumphs have been
achieved. Had it not been for Mr. Stephenson's un-
flinching energy in maintaining his opinions, single-handed,
against large majorities, the country and the world might
have remained for many years without the advantages
which our railway system has conferred upon all classes
of the community.

It is an agreeable task to enumerate the merits and pay
tribute to the memory of men who have done so much for
their country. The name of George Stephenson will stand
beside those of Brindley and Telford and Watt, amongst

FBOGBESS OF ENGINEERING. 243

the pioneers of progress by whose aid mechanical science
and art have attained their present high state of per-
fection.

In conclusion^ I can only allude in passing to one of the
greatest wonders of our age, the electric telegraph ; and
although not, strictly speaking, within the province of
mechanical art, it may safely be included among the
achievements of the last half century of which we have
been speaking. The phenomenon of the electric cur-
rent, when practically employed in the transmission of
intelligence, cannot be viewed in any other light than
the crowning triumph of the age ; and it must ever be
a subject of congratulation to us that in our lifetime
the spark of heaven — ^if I may use the expression — was
commissioned to be our swift obedient minister in con-
veying thought and intelligence from man to man (ir-
respective of distance or of time) to the remotest parts
of the earth.

B 2

244

LECTXJRE V-

THE STBENGTH OF IROK SHIPS.

[Bead before the Polytechnic Institute in Liverpool, and at the opening
Session of the Institute of Nayal Architects in London.]

It is nearly thirty years since the construction of iron
ships for sea-going purposes was first entered upon ; and I
believe I was the first to show, in conjunction with Messrs.
John and McGregor Laird of Birkenhead, the superior
strength and security of iron vessels. After a long series
of experiments in the construction of different forms and
dimensions, it was found that the resisting powers of an
iron vessel, when properly constructed, could be depended
upon for navigating the open sea, and was much better
calculated, as respects lightness, capacity for cargo, &c.,
than one composed of tiie best English oak. These con-
siderations induced Messrs. John and McGregor Laird
and myself to commence iron-ship building on a large
scale, and thus to realise an expensive and laborious series
of experiments on the value of these constructions. Hence
I founded the works now occupied by Messrs. John Scott
Kussell and Co. at Milwall, London, in which establish-
ment (carried on under my own direction from 1835 to
1848) upwards of one hundred vessels were built; and the
applicability of iron to the purposes of naval architecture
was then and has since been fully demonstrated in the con«
struction of several splendid steamers, such as the Great

RECENT TENDENCIES. 245

Britain, the Persiay and the Great Eastern, and also of
sailing vessels of very large tonnage.

But although considerable improvements have been in-
troduced in the design and construction of iron vessels
during the last quarter of a century, the subject does not
seem to have been theoretically or practically investigated
to the extent to which the importance of the subject so
justly entitles it. My own experiments related chiefly to
the strength of the material itself, its distribution, and the
value of different kinds of riveted joints as compared with
the solid plate.

Nothing has^ however^ been done, so far as I know^ in
determining the strength of an iron ship en masse; and the
object in view in the present paper is to inquire into the
strength of iron vesseU as they have been and are now
constructed, and to ascertain if there exist any hidden
weakness which may be remedied by a more judicious
distribution of the material.

Of late years it has been found convenient to increase
the length of steamers and sailing vessels to as much as
eight or nine times their breadth of beam ; and this for
two reasons : Jirst, to obtain an increase of speed by giving
fine sharp lines to the bow and stern ; and, second, to
secure an increase of capacity for the same midship-section,
by which the carrying powers of the ship are greatly aug-
mented. Now, there is no serious objection to this increase
of length, which may or may not have reached the max-
imum. But unfortunately it has hitherto been accom-
plished at a great sacrifice of the strength of the ship.
Vessels floating on water and subjected to the swell of a
rolling sea — to say nothing of their being stranded or
beaten upon the rocks of a lee shore — are governed by
the same laws of transverse strain as simple hollow beams
like the tubes of the Conway and Britannia Tubular

B 8

246 JBON SHIPBUILDING.

Bridges. Asauming this to be true, and, indeed it scarcely
requires demonetration, it follows tliat we cannot lengthen
a ship with impunity without adding to her depth, or to
the aectional area of the plates in the middle.

If we take a vessel of the ordinary construction, or what
some years since was considered the best construction,
300 feet long, 4 1 feet 6 inches beam, and 26 feet 6 inches
deep, we shall he able to show how inadequately she is

Fig. 44.

designed to resist the str^ns to which she woald be sub-
jected. Such a vessel would be sheathed with plates -j of
an inch thick (working transversely from the keel to the
deck on each side) for 13 feet on each side of her keel, £
inch plates for a distance of 10 feet 6 inches round each
side of the bilge, and ^ in(^ plates for the remainder to
the upper deck; her keel would be 12 X 4 inches, with

ORDINARY CONSTRUCTIOK.

247

plates on each side 2 feet wide by 1 inch thick, and in ad-
dition to this there would be a hollow stringer, similar to
fig. 44, 18 X 12 inches, riveted to the angle-irons of the
frames 2 feet 3 inches above the keel. At the top of the
upper deck are two plates and angle-irons, forming an
open box b, fig. 45, on each side 18 x 12 inches, which,
together with two small stringers along the deck and two
at the sides, as shown at a a and b by fig. 46, would con-
Fig. 46.

stitute the only power for resisting a tensile or compres-
sive strain arising from transverse flexure.

On referring to the midship-section of a vessel of these
dimensions, fig. 46, it will be seen that the upper deck is
not constructed so as to give stability to the ship, and is
totally out of proportion with the quantity of material in
the other parts of the hull. If we take a vessel such as

B 4

248 lEON SHIPBUILDING.

we have described and shown in fig. 46, and which, it
must be admitted, is of inferior construction, we shall
approximate nearly to the facts by treating it as a simple
beam ; actually a vessel is placed in this position, either
when supported at each end by two waves or when rising
on the crest of another wave, supported at the centre,
with the stem and stern partially suspended. Now, in
these positions the ship undergoes alternately a strain of
compression and a strain of tension along the whole section
of the deck, corresponding with equal strains of tension
and compression along the whole section of the keel, the
strains being reversed according as the vessel is supported
at the ends or the centre. These are, in fact, the alternate
strains to which every long vessel is exposed, particularly
in seas where the distance between the crests of the waves
does not exceed the length of the ship.

It is true that a vessel proportioned like the above sec-
tion will continue for a number of voyages to resist the
continuous strains to which she is subjected whilst resting
in water. But supposing in stress of weather or from some
other cause she is driven on a rock with her bows and
stem suspended, in the position shown in the sketch,
fig. 47, the probability is that she would break in two, se-
parating at T from the insufficiency of the deck. This
is the great source of weakness in wrought-iron vessels of
this construction, as well as of wooden vessels when placed
in similarly trying circumstances.

To prove this, let us give the vessel already described
the full benefit of being considered a well-constructed
beam, which indeed is more than we may expect; and
applying the formula,

adc

W«

which would then be applicable, we shall find her powers
of resistance comparatively small.

250 IRON SHIPBUILDING.

The sectional areas of wrought iron we shall find to be
as follow :

Inches.

Square inches.

Keel

. 12x4 .

. 48

Hollow stringer

. 18x12 .

. 46

Sheathing .

. 812x| + 252x|

. 462

Plates at keel

, 48 X 1 .

. 48

Total area

of bottom

. 604

To balance this area at the bottom^ we have at the top^
taking the sheathing-plates to a depth of six feet below
the upper deck :

Square inches.
Stringer-plates and open trough-plates . . .190

Side-plates, to a depth of six feet on each side . .110

Deck-planking . . . • . .100

Total «raa of top .... 400

The deckxplanking, which to a limited extent contri-
butes to the resistance to a tensile strain^ might be taken
at one-sixth the resisting powers of iron^ or equivalent to

41-5 X 1^ x 6 ^ ^jQ gq^^ .jj^i^gg .

but the entire absence of longitudinal joints reduces this
resistance much farther^ and we have, therefore^ con-
sidered the resistance of the deck-planking to be equiva-
lent to a section of 100 square inches of wrought iron.

Now if we apply the formula for beams, we have, for
the constant, c=60, on account of the joints being only-
double riveted; flr=:400 square inches; rf=the effective
depth, which, since the side-plates have been taken for a
distance of six feet from the deck, could not exceed 24
feet; /= length =300 feet; hence the centre-breaking
load is equivalent to

^^400K24x60^^g^Q

800 '

or in other words, a weight of 960 tons suspended from

DEFICIENT STRENGTH. 251

bow and stem^ apart from the vessers own weight, would
cause her to break asunder.

We may verify this calculation by another^ in which
the strength is calculated from different data. If we sub-
stitute for the area of the top the whole midship area of
the vessel, and for c=60 substitute C = 18'3, we get,

W=ii22jl^lilii?« 20496 tons,
300

which gives a close coincidence of result with the previous
calculation.

If, however, the deck-beams were covered with iron
plates throughout the whole length, on each side of the
hatchways, so as, by a new construction, to render the
area at the deck equal to that at the bottom, we should
then have for the centre breaking weight

W » 60^^26-5x60 = 3200 tons,
300

or nearly twice the strength given in the preceding case.

If we now consider the amount of displacement in
tons in the vessel we have described, we shall find that
the margin of strength is far from satisfactory. When
loaded to a depth of 18 feet draught of water, the dis-
placement would be about 177,000 cubic feet, which is
equivalent to a weight of about 5000 tons for the ship
and cargo. If we consider this weight as uniformly dis-
tributed, and compare it with the strength we have deter-
mined, we have.

Tons.
Load uniformlj distributed ..... 5000

Breaking-weight with load distributed, 1920 x 2 . . 3840

Leaving a deficiency or source of weakness equivalent to . 1 160

80 that it is evident that if laid high and dry, in the
position shown in fig. 47, she would break with |-§^ or |^ of
the load which she actually carries. Under ordinary cir-

252 IKON SHIPBUILDING.

cumstancesy it is true that a vessel could never be placed
in such a position^ unless when stranded on a lee shore^ or
under circumstances where each receding wave would
leave her with not more than six or eight feet of water
over her keel^ and in these conditions she must inevitably
go to pieces.

I refer to these extreme cases because our iron con-
structions, in which we risk so much life and property,
may be exposed to even this degree of danger, although
circumstances so critical do not frequently occur. If we
might suppose material added to the deck-section, either
by iron plates under the planking or in any other form, so
as to give an area of wrought iron equivalent to that of
the bottom, or 604 square inches, the strength would be
nearly doubled, but would still be short of an adequate
margin for security to resist the force of impact, as the
waves lifted the vessel and dashed her again on the rocks.
It may be urged that this is an extreme case ; but it is an
extreme such as we must guard against, and vessels ought
in every case to be built of suflBcient strength to secure
them from failure in all the conditions in which it is
possible for them to be placed.

Having shown the imperfect state of our constructions
from an example selected from the earlier stages of iron
shipbuilding, I would now direct attention to the most
recent forms of iron vessels.

It will be observed from the following diagram, fig. 48,
that considerable improvements have been effected, both
as regards strength and the distribution of the material,
since the infancy of iron shipbuildings when the properties
of the material and the results of its combination were
very imperfectly known. It is now widely different;
and though still far from perfection, it is nevertheless of a
character which gives greatly increased security to life and
property.

DEFICIENT STRENGTH.

253

Let us, for example, again take a vessel of the present
build, and compare it with that of its predecessor of ten
years ago, which I have already described.

Fig. 48 is the cross midship-section of a vessel of the
present build, and clearly shows the improvements which

Fig. 48.

have been effected. The sectional areas of the upper deck
of this vessel, which is of the same size as the preceding,
are as follows :

Square inches.

Open trough-plates on deck, and plates on each side, as

before, to a depth of six feet under the deck . .176

Stringer-plates . . . . . « 165

Add to this, as before, for timber of decks . .100

Total area .... 441

where the area is larger than before, and the strength,
although still deficient on the deck, would be increased
from 3800 to 4200 tons, which is much in favour of the
security of the ship.

Taking another vessel (fig. 49) of still more recent con-

254

IRON SHIPBUlLDINa

struction, 235 feet 6 inches long, and 35 feet beam^ and
22 feet 9 inches depth of hold, and of a burthen of 1500
tons, we find a still better disposition of the material as
respects the strength and durability of the ship.

Taking the area of the above vessel, we have as under :

JEx. £l • •

B B • •

c c * •

c c » •

Side-plates, taken at
Deck-planking, say .

Total area

7'6"x|x2

2' 9"

x4^x 2

13
16

2' 9" X I X 2

2' 0" X 11

Square inches.

. 112-5

. 107-2

. 30-0

. 16-5

. 80-0

• J^

. 432-0

which, by formula, assuming the bottom section to be in
excess of the top, would give 4600 tons as the distributed

Fig. 49.
bI I " ^ -^ A. \ It^

breaking weight for a smaller vessel. This is, however,
still short of the required proportion, and admits of fur-
ther improvement, as we shall presently show.

Having now directed attention to existing defects in
the construction of iron vessels, I may venture to proceed

DEFICIENT STRENGTH. 255

to the more important consideration of their removal, by
passing from a system of apparent guesswork to a careful
adherence to sound principles in design^ like those esta-
blished by direct experiment for other constructions go-
verned by the same laws and subject to the same strains.
If I am correct in treating iron vessels in the light of sim-
ple girders, I shall be able to show a better disposition of
material, calculated to remedy present defects, and greatly
increase the strength of vessels, without any great increase
of cost, to resist transverse strains. If I were proceeding
upon theoretical considerations, the results I have stated
might be doubted ; but we have a sufficient number of
experiments upon hollow wrought-iron girders to calculate
the strength and resisting powers of ships to transverse
strain, with a near approximation to accuracy in the
results.

Let us, therefore, again take the case of a vessel 306
feet long, 41 feet 6 inches beam, and 26 feet 6 inches deep,
built according to Lloyd's rules as an Al vessel of the
highest class, for twelve years, from dimensions given in
Table G. In such a vessel we have the best known con-
struction, according to the highest authority, and although
I do not wish to find fault, or in any way question the re-
gulations of Lloyd's, which appear to have been drawn up
with great care, yet I am of opinion that they may be
greatly improved upon by the following alterations. Let
us suppose the vessel to have a displacement of 5600 tons,
and to be constructed with a midship-section exactly simi-
lar to what is required in the regulations of Lloyd's. In
this section (shown in fig. 48), not only is the deck section
defective in its resistance to a tensile or compressive strain,
when compared with the bottom, but following up these
rules, as laid down for the guidance of builders, two very
important points seem to require revision, namely, that
they make the strength of materials in vessels to be in

256

IRON SHIPBUILDING.

proportion to their tonnage, without reference to their
length, and also that they require the plating, stringers,
and frames at the ends of the vessel to be about the same
weight and strength as at midships. Now it is at the
latter part where the strength is required, as in every
case the strain is greatest there, and gradually diipinishes
towards the. stem and stern. In fact, the section of the
plates and stringers ought to be double at midships, both
at the deck and the bottom of a well proportioned ship.

To illustrate these facts, it will be necessary to estimate
the strength of a vessel constructed according to the latest
regulations of Lloyd's, for the highest class, Al vessels,
and then to point out the distribution of material which
will secure perfect uniformity of strength.

Taking the length at 306 feet, beam 41 feet 6 inches,
depth 26 feet 6 inches, we have the sectional areas :

Square Inches.

. 42-0

. 31-5

. 13-7

. 20-0

For the keel •

Floor or bottom plates •

Keelson

Angle-iron . .

Bottom -plates .

Two stringers and angle iron

Two

»♦

498-0
66-0
18-0

689*2

Total area

Again, if we take the sectional area of the deck and
six feet down the sides (which is a fair average of its
powers of resistance to tension and compression), and
allowing 130 square inches of iron as an equivalent for
timber-stringers, deck-planking, &c., the area will be as
under :

Square inches.

Side-plates . . . . . .144

Two stringers and angle-iron
Two stringers on lower deck, say
Timber stringers and planking
Two midship stringers .

Total area

130

395

STRENGTH NOW PBOPQSED. 257

Here it is evident that there is a great want of propor-
tion between the top and bottom of the ship^ and in orde^
to attam the maximum point of strength, we must in-
crease the area of the top, retaining the bottom as hitherto
constructed.

Let us assume the displacement of such a vessel to be
5600 tons ; then, in order that she may be capable of sus-
taining half that weight suspended from her centre, or
5600 tons equally distributed inclusive of her own weight,
she would require a midship-section of at least.

Square inchei*
For the bottom .»•••• 535
For the top • . , • < • 535

For the intermediate space • • • • 130

Total area • « • . 1200

Giving by formula,

^^26-5x535x60^
306

the breaking-load in the centre.

Now, in order to be secure against the vessel's breaking
in two when placed in a position such as already described,
we must give her a still larger margin of strength, and, in
fact, make the deck as strong as the bottom in the section
of Lloyd's, and we should then have by the same formula,

^^690x60x26'5^3g3g
306

or 7170 tons equally distributed throughout the ship. In
the present state of our knowledge, it would appear that
we are greatly deficient in the application of those laws
which determine the strength of ships and other similar
constructions ; and as I have laboured for the last thirty
years to determine these laws experimentally, I may pro-
bably be excused if I now seek to establish sounder prin-*
ciples of construction in this all-important branch of
engineering — the increased security of our mercantile
marine.

258 IBOK SHIPBUILDINO.

In our present Al iron -vessels, it is evi<3ent, according
to Lloyd's regulations, that we have only 400 inches of
material at the deck to balance 690 inches at the keel, and
that if suspended on rocks, in the position already dis-
cussed, the ship would inevitably be destroyed with a less
weight than she is actually accustomed to cany. In this
Lecture I am advocating a principle calculated to pro-
vide against such a contingency, viz. that vessels of this
description should be constructed with equal sections at the
deck and keel, say each about 690 square inches. They
would then he equally strong, whether in the position
«hown in fig. 47^ or whether suspended on rocks at each
end, in the position shown in fig. 50, with a compressive

Fig. 60.

strain along the top, and a tensile strain along the keel.
In either position there would be a auiplus strength of
fiOO tons to spare as a margin against every contingency,
or by whatever forces she might be assailed. Generally, I
have contended for equtil sections at the top and bottom ;
but cases may arise where stronger bottoms are necessary,
as in screw colliers, which take the ground, but in other
cases, the nearer the deck and bottom approach each other
in sectional area the better.

It may be said that vessels constructed upon this prin-
ciple would be greatly increased in original cost. To
eume extent, no doubt, this is true ; but the material accu-

DISTBIBUTION OF MATERIAL, 259

xnulated towards the middle should be progressively re-
duced towards the stem and stern. Thick plates and
large masses of iron are not required at the extremities,
if uniformity of strength is to be attained. It is an utter
waste of material to introduce it where, it is not wanted,
and, moreover, where it does not add to the security and
stability of the ship. In fact, I would earnestly urge upon
the attention of builders, that more care should be exer-
cised in proportioning different parts to the strain they
have to bear. I do not mean that the frames and sheath-
ing-plates should be much reduced in size or thickness,
but the longitudinal stringers and side-plates may be re-
duced in thickness to advantage. For example, if we take
the deck-stringers and longitudinal stringers, which I re-
commend in order to give increased security, they should
be proportioned as shown in fig. 51, These numbers

Fig. 51.

Halflengfh 150 feet.

approximate to the true proportions for equal strengths ;
and the only deviation from these ratios should be in some
parts of the exterior sheathing (probably at the bows,
should the vessel come in contact with floating ice), bulk-
heads, frames, &c. In this way a great deal of material
would be saved which does not add to the strength of the
vessel.

Another feature in the construction of iron vessels is
the method of forming the riveted joints. I am perfectly
cognisant of the custom of double riveting, which is suffi-
ciently strong in the longitudinal, but comparatively weak
jn the transverse, joints. These latter ought to have long
covering plates, and should be chain riveted, as shown in
fig. 52. If the joints were made on this principle, it

8 2

260

IBdN SHIPBUILBIKGk

would add twenty per cent to the transverse strength of
the ship^ — an important desideratum^ and one which would
be attained at the expense of a few more rivets and a small
increase in the length of the covering plates. The secu-

Eig. 52.

rity of the ship should not be jeopardised for such a con-
sideration ; and it is to be hoped that vessels will not in

Fig. 53.

future be built at a loss of one-third of the longitudinal
tenacity as at present^ but that the most perfect mode of
uniting the plates will be adopted in every part of the

OBAIN BITETINQ.

261

ctonstniction. If the principle of dmin riveting were
adopted, we might employ the constant 80, instead of 60,
in the formula for calculating the strength, and the weight
and sectional area of the plates might then be reduced.
This is a consideration of
much importance, as the ^- "*•

frames, or rihs, might he
made two feet six inches
apart to admit the necea-
eary covering plates, and
secure a better system of
transverse joints, as shown
in figs. 52 and 53. Selow
water, where awater-tight
joint is the first requisite,
the rivets must be placed
nearer together at the joint;
but we may still compen-
sate for the loss of strength
caused by the closeness of
the rivets, by using a cover-
ing plate thicker than the
plate, and countersinking
the rivets on the outside,
as shown in fig. 53. It is
true that builders are not
allowed, by Lloyd's rules,

to place the frames more 7

than eighteen inches apart,
which only permits double

riveting; but Mr. Vernon, whom I consulted on these points,
and to whom I am indebted for many useful suggestions,
informed me that, even with frames at this distance, each
alternate tier of plates might be so riveted ; the plates
being arranged outside and inside, aa shown in fig. 54,

2i62

IRON SHIPBUILDIKG.

\rider covering plates might be introduced, as shown at
a Gy under the angle iron of the frames^ and thus the outside
plates chain riveted. This would be a great improvement,
and add considerably to the strength of the ship. As
respects the diameter of the rivets and their distances
apart, the following table, deduced from experiment, and
employed by myself and and others in extensive practice,
may be relied upon.

Table exhibiting the best proportions for riveted joints.

Thickneii of

platei in

inches.

•19
•25
•31
•38
•50
•63
•75

3
iff

4
IS

5
36

6
I6

16
10
13
12
Iff

Diameter of

rivets in

inches.

•38"^

•50
•63
•75

•94U-5
1^13J

Length of ri-
vets from the
head in inches.

•881
M3
1-38
1^63
2*25
2^75
3-25 J

► 4-5

Distance of ri>

vets from cen^

tre to centre

in inches*

1-50 J

1-63 U
1-75 J

2-50 [ 4
300 J

Quantity of

lap in single

joints in

inches.

1-25 1
1-50 1 6

rssJ

2-00 5-5
2-25 "I
2-75 \ 4-5
3-25 J

Quantity of
lap in double-
riveted joints
in inches.

Add two-
thirds of the
depth of the
single lap.

I now venture to direct attention to the plan which I
propose should be adopted for securing the most effective
distribution of the material which is to be added to the
upper part of the ship. Iron vessels are ordinarily con-
structed with ribs or frames^ placed from fifteen to eigh-
teen inches apart. They are about two feet deep at the
keel^ and taper to the width of the angle-iron round the
bilge on each side, at «, fig. 48. From that point to the
top of the deck, the angle-iron is in some cases considered
of sufficient strength for the reception of ^Jie sheathing-
plates. On the top side of the ribs a lighter description
of angle-iron is riveted, and to this the flooring, whether
of wood or iron, is attached. This plan of construction is
not objectionable, provided two more longitudinal stringers^

PROPOSED ADDITIONS.

263

on each side of the keel^ are made to run from one end
of the ship to the other, and in large ships chain riveted,
as previously recommended, which will greatly enhance
the value of the ship. If this were done so as to give the
required midship-section necessary for the security of the
vessel, it would prove highly advantageous.

The Chreat Eaaterriy which is probably the strongest
vessel in proportion to her size ever built, is constructed
on this principle ; and the designer, the late Mr. Brunei,
was too sagacious an engineer to lose sight of the cellular
system, developed first in the Britannia Bridge, to neglect
its application to the deck as well as the hull of the monster
ship.

Fig. 55«

The result of this application, with the longitudinal
bulkheads^ constitutes the enormous

• 4

strength of this

264 IBON SHII»BnrLDIK(»r

magnificent vesael, proving the importance of the cellular
system for vessels of large tonnage. It combines lights
ness with strength, and the double sheathing gives immense
rigidity to the construction ; in fact, the Great Eastern is
a double ship up to the water-line. With smaller vessels,
however, this system is not applicable ; but a modification
of it, as shown in fig. 55, may be safely adopted with
advantage to both builder and owner. The exchange
from the old system to the one I am urging will not call
for any great sacrifice ; the change I propose is a new and
more scientific distribution of the material, and not any
great increase of sectional area, and consequently of weight
throughout the construction.

In the formation of the deck, it is essential, for public
security, that a new principle of construction should be
immediately adopted, and that the cross-beams forming the
upper deck should be covered with iron stringer-plates,
thickest towards the middle of the vessel, and tapering
from i to 3^ inch thick as they approach the stem and
stern. The sectional area thus obtained, however, is
short of what would be required for a vessel of the mag-
nitude we have been considering. To secure a propor-
tionate resisting power in the deck, we shall require the
arrangement shown in fig. 65, giving an area of 750
square inches, exclusive of the hatchways, which I have
estimated at 8 feet wide. This sectional area would be
distributed as follows : —

Section of Longitvdinal CelU, dd.

Square inches.
2 plates, 26|" X I" ..... 38*0

6 plates, 18" X f" 81-0

8 angle-irons, 3" x 3" x f • , , . 26*8

FBOPOSED ADDITIONS.

265

SeciioH of Comer Cdls, ce*

Sqture inches.

6 angle-irons, 4" X 4" X 1^'

. 27-6

2 n 6|"x5rx|" .

, 150

2 plates, 31'' X J'' . . • ,

. 54-0

2 „ 48" x|/' • • • .

. 84-0

2 „ 33" xj" . . • .

. 67-7

2 „ 72" xl" • . . •

. 144*0

Oiher Platea.

4 stringers, 24''x|/' . . . •

. 840

2 stringers on lower deck • • •

. 250

Deck-timbers, say .

. 120-0

Total area of top . ,

• 7671

Section of Bottom,

1 keel, 12" x 3J"

. 420

2 plates, 31" X 1^" , . , .

. 660

2 lengths, 246" X 1" . . . ,

• 492-0

12 angle-irons, 6j" x 6|" x |" .

• 90-0

2 bulb-irons, lOj" x f" .

, 18-0

Keelson, 18" x |" .

. 15-75

2 plates, 25" xf" . . . ,

Total area of bottom •

• 37-5

• 761-25

Thus we should have in the hull and deck a maximum
£.rea of security ; and the vessel^ so far as regards her
uUimate strength^ would be superior to any tests to which
she alight be subjected at sea or on shore. Under the
most trying circumstances she would not incur the risk of
breakings and the passengers and cargo would in all pro-
bability be secure.

In these recommendations we have not desired to teach
the experienced shipbuilder the details of his business ;
all we contend for is greater security for life and pro*
perty^ obtained by adherence to sound principles of con-
struction of well-ascertained truth. In furtherance of
these objects^ I would venture to suggest the following
improvements and additions to the midship-section of
iron vessels, viz. the introduction of two cellular rectan-
gular stringers, . one on each side of the hatchways^

266 IBON SHIPBUILDING.

and two triangular stringers^ one on each side of the
vessel^ as shown in fig. 55. a a is the wooden deck^
under which is a platform of |-inch plates, riveted
to the light beaips £i,. which rest on the two triangular
cells cc, to which they are riveted, as also to the rectangular
cells dd, which run the whole length of the ship, and rest
on the water-tight bulkheads, which divide the ship into
eight separate compartments. These cells should be
chain-riveted, and by the same means to be attached to
the angle-iron of the bulkheads on which they are sup-
ported. These Will diminish the span of the cells and
lighten the deck-beams, which will not exceeed 15 feet in
length from the cells dd to the side of the ship. It will
not be necessary to go farther into detail, as the cross-
beams and gusset-stays to the lower deck are of much
less importance than the corresponding parts in the deck
we have considered. *

As respects the quality of the iron used for ship-
building, tlie greatest care should be observed in the
selection. Twenty to thirty shillings a ton will make all
the difference between good plates and worthless ones^
and no plates ought to be used which will not stand an
average tensile strain of 20 tons per square inch. The
better qualities of plates vary from 20 to 25 tons per
square inch; but well-wrought plates, free from dross,
and equal to an average test of 20 tons per square inch,
will give to the vessel, if well constructed, adequate
durability and strength.

It is from this material (iron) that we derive the instru-
ments of our civilisation ; our progress in useful art
depends upon our knowledge of its application ; ships of
400 to 700 feet in length, and bridges of equal span,
could never have been attempted in its absence; in its
varied forms and conditions, it supports our wonderful
industry, and is the soul of our commerce. Viewing it in

QUALITT^OF IRON. 267

this light, how important is the development of every
new law and every new application which tends to secure
its economical employment I and looking at our continued
progress in our knowledge of its properties, and its conver-
sion from the crude ore to its final condition in its various
applications, we may say that the iron age of the world
has come, nourishing a never-failing and widely-extending
industry, — an industry which has raised this highly-
favoured country to the position of the leader in practical
science, and the pioneer of progress.

Having thus pointed out the defects and the remedies to
be applied for giving increased security to iron ships, it
simply remains for me to urge upon the merchants and
builders in this great community the absolute necessity of
adherins^ to the fixed and determined laws of physical
truth which I have endeavoured, however imperfectly, to
inculcate; but which, if carefully followed, will greatly
extend our iron constructions, and render the iron ship o£
British manufacture triumphant on every sea.

268

LECTURE VI.

ON THE CONSTRUCTION OF IRON VESSELS EXCEEDING
THREE HUNDRED FEET IN LENGTH.

In the previous Lecture I endeavoured to inculcate prin-*
ciples on which iron ships ought to be built in order to
secure perfect safety^ and to give to the public increased
confidence in the stability of these constructions. In
pointing out how these desiderata may be obtained^ I con*
fined my attention to vessels varying from 500 to 1500
tons burden,.. and not exceeding 300 feet in length and.
41 feet 6 inches beam. In these constructions I attempted
to prove that the present system was defective, and that
in certain positions a vessel built upon this principle must
of necessity break up and go to pieces. These views
were not founded upon theoretical speculations, but upon
experimental facts, and to which I considered it my duty
to direct public attention.

It cannot be denied that the most disastrous effects
have followed from these defects ; and it appears impera*
tive, for the sake of life and property, that a new and more
perfect system of construction should be adopted, founded
on definite laws by which the resisting powers of materials
in different forms and conditions are governed. As re-
spects iron nearly the whole of these laws are known, and
we are at no loss to discover its ultimate powers of resist-
ance in whatever positions it is placed, or to proportion its

THE CELLULAB SYSTEM. 269

dimensions to meet with safety the forces to which it is
BubjectedL Possessing this knowledge^ and having it in our
power to apply it^ why should we neglect its application
in structures of such vast importance as those in which
our lives and fortunes are so often embarked ? The sur-
veyors of Lloyds^ most excellent^ well-meaning, gentle-
manly men as they are^ may say what they please^ but I
have no hesitation in stating that their regulations are
very defective and require immediate revision, and such
a revision in my opinion should be based upon principles
of exact science^ and calculated to secure a maximum
strength in the iron ship. I do not wish to find fault, nor
do I assert that the alterations I have to propose are in
every sense the best calculated to produce a maximum
effect; on the contrary, they may require correction in
practical details ; but this I believe, that the present build
of ships is decidedly imperfect, and admits of great im-
provement both as regards security and economy in the
use of the material of which they are composed.

The cellular system has been objected to on the ground
of the inconvenience of longitudinal stringers along the
deck on each side of the hatchways, and their liability to
oxidation. Now, so far as regards the deck these objeci
tions have in reality no weight, for the proposed cellular
stringers need not exceed fifteen inches square^ or eighteen
inches wide by fifteen deep ; and these, with the cells which
form part of the bulwarks^ will afford all that is wanted to
give the required stability to that part, forming, if pro-
perly put together, perfectly rigid horizontal columns to
resist the force of compression on the one hand, and ten-
sion on the other. Again, as regards oxidation, none can
occur to any injurious extent so long as these cellular
stringers are below deck and are riveted water-tight,
which may be done with perfect safety and without dimi-
nution of their strength. From these remarks, and from

270 , IRON SHIPBUILDING,

previous statements it will be seen that the excess of
material is not required in the vicinity of the neutral axisp
where the strain is least, but at the extreme top and
bottom, where the strains are most severe when the vessel
is pitching in a heavy sea.

It is a universal law of construction that the resistance
provided for should be proportional to the assailant force
in each part, and in order to effect security it should
nlways be greatly in excess. In building a ship, as in other
similar structures, the first thing is to ascertain the pointa
of greatest strain, and to provide at those parts the greatest
power of resistance ; but to build a ship with equal thick-
nesses of plates throughout, or any other vessel liable to
be ruptured by forces that act with double the intensity
in some parts that they do in others, is not only a great
waste of valuable material, but is absolutely injurious, in
BO far as it adds by increased weight to the destructive
element that tends to break up the vessel. This being
the case, how essentially necessary is it that the strengths
should be carefully proportioned to the strains, and the
material arranged in such a form as to offer a harmonioua
resistance to the forces thus acting upon it.

To effect this distribution, the object of the previous
investigation, and keeping in view the same principles I
there ventured to advocate, I now come to a larger class of
vessels, which involve at the present time considerations of
vast importance to the owners and builders and others
interested in the extension of commerce. To these vessels
I would now venture to apply the same principles, so as, in
xny opinion, to secure the necessary strength under the varied
forms and circumstances to which they are subjected.

We do not know what changes are in store for us as a
result of the performance of the Great Eastern; that
vessel has not yet been fully tried, and it would be premature
to anticipate results ; as it is, we can only assume that she

QUALITY OF IRON. 271

will prove commercially successful, and although probably
not to the extent expected by her more sanguine advo-
cates, yet that she may possess qualities favourable to a
considerable increase in the dimensions of our vessels both
in relation to their capacity for cargo, speed, and other
good properties. If we assume this as the result of the
forthcoming performances of the Great EcLsterriy we may
take as the basis of our inquiry a vessel of 500 feet length
between the perpendiculars, and 68 feet beam. The ques-
tion for consideration then is, on what principle should she
be built for the purpose of attaining the greatest security
with the least material ? To answer this inquiry we may
consider; —

Ist. The general principle of construction.

2nd. The frames and ribs, and their distribution as
affecting the transverse strength.

3rd. The plating or sheathing, including stringers, cells,
&c., as affecting the longitudinal resistance to fracture,

4th. The decks, bulkheads, and internal fittings.

5th. The bows and stern in their resistance to con-
cussion.

6th. The resisting powers, durability, and economy of
the ship taken en masse.

In our attempts to apply sound principles in construc-
tion, we have two things to determine : — first, the proper-
ties of the material we have to deal with, and second, the
forms and conditions in which it should be applied. In
regard to the former, it is essential to sound construction
that we should have good material, and on this point it
will be requisite to offer a few suggestions. To those ac-
quainted with the iron trade, it is well known that we have
five or six different sorts of plate and bar iron, namely,
cinder plates, common plates, best plates, double wrought
plates, and the superlatively good best- best plates. The
same varieties may be had in bars, and it requires no

272

IBON SHIFfiUILDIl^G.

small degree of ekill and penetration to determine from
appearance what is good and what is bad. One thing is
however evident^ that no description of plates or angle
iron should be employed in shipbuilding that would not
stand a test of 20 to 24 tons tensile strain per square inch.
That these plates should be made from good puddled bars«
piled and rolled at the proper heat^ is also essential to
durability and security in naval construction; and the

Fig. 56.

additional cost of 20s. per ton should not be an object when
compared with the superior quality of the iron employed.
In fact^ it is a mistaken economy to suppose that a reduced
rate per ton in the first cost of an iron ship is an advan-
tage. On the contrary, it involves in reality a serious loss;
the inferior material can never be depended upon, and
the risk incurred in consequence is too great to lend to its
employment any countenance or support On the other
hand, when a better quality of iron is used^ less weight is

THE CBLLULAB SYSTEM. 273

rei^uired, and the builder executee hia work with greater
exactitude and with leas risk of injury to the material.

Aseuming that the material is unexceptional as to qua-
lity, we have next to consider the principle on which huge
vessels, 500 feet in length, should be
constructed for the purpose of obtaining
the maximum of strength with the least
material. In this case it will be neces-
sary to depart from the ordinary rules
of construction, and instead of a closely
packed series of transverse frames, it will
be important-to place the principal frames
at diatances of 4 feet apart, using the
remainder of the material in the shape
of longitudinal keelsons or stringers, as
shown at a a, fig. 56.

Framing the hull of the ship in this
form gives greatly increased stability, ^
and in a vessel of this magnitude the ^
whole of the material in her hull will n
be arranged in parallelograms, measuring
at midships € feet by 4 feet, and nar-
rowing as they approach the stem and
etern until the lines of the vessel bring
them in contact, at which point two cells
would run into one till the extreme points
were reached at each end. If we re-
move the iron sheeting, the bottom of
the ship will present a large honey-
combed surface, as in fig. 57. Now of
all forms this is the strongest, and a lat^e
vessel constructed in this way would
have immense rigidity, and form one
continued line of walls or girders, greatly in favour of
the material, and adding macfa to the strength of the ship.

274

IRON SHIPBUILDING.

Besides^ in the above form the plates forming the keelsons
and frames may be much reduced in thickness^ and two*
thirds of the transverse frames being dispensed with, we
can afford to increase the number of longitudinal keelsons
without increasing the weight of the material in the ship.
For comparison, let us estimate the strength upon this
construction and that on the plan of frames 18 inches
apart, with only three longitudinal keelsons in the bottom.
In the proposed improvement there are 13 longitudinal
keelsons, and these, with the outer and inner sheathing at
the bottom, cellular deck, &c. would probably give a dis-
placement of 4500 tons.

1. Centre keelson

2. Keelsons

Area of Bottom,

Ft. Ft. In.
500 X 6 X I and angle iron

»»
n
tt

4 X

3| x|
3 x|

2 x|

»»

Total keelson area
80 feet of sheathing plates averaging | in. thick
60 feet interior sheathing averaging | in.

Total area of bottom

Sq. ins.

. 72

. 90

. 132

. 60

. 54

. 48

.456
. 720
. 270

1446

We suppose the upper part of the ship along the deck
to be formed on the same principle as advocated for ships
of 300 feet length in the previous lecture, with two cells
near the centre, b ft, and with two square and two tri-
angulsCr longitudinal cells, c c, at the side, extending the
whole length of the ship, as shown in the section, fig. 56.
We should then have with the stringer plates, deck plank-
ing, &c., the following sectional area : —

THE CELLULAR SYSTEM.

275

Area of the Top,

2 middle cells 20 in. x 20 in. x |in. .

2 side cells 30 in. x 18 in. x fin.

2 triangular side cells 36 in. x 36 in. x | in.

Angle iron to the above ....

16 feet of plates on sides «» 192 in. x fin. .

Deck stringers 360 in. x 1 in.

Deck planking, say

Total area of top .

Sq. ins.
120

142

162

138

144

360

300

1366

This gives an excess of 140 sq. ins. in favour of" the
bottom as a compensation for extra wear and tear on that
part.

The strength of a vessel built in this form with the
above sectional areas, and properly constructed to resist a
lateral strain, may be found as before by applying the

formula W = -^, With the constant 60 as before, and
taking the smaller or deck area, —

a = 1366
d=^ 40
1366 X 40 X 60
500

c= 60
/ = 500

= 6556*8 tons

the breaking weight at the centre, or 13,1 13*6 tons with
the load distributed. Again, comparing this with the
weight of the ship and cargo, and taking her loaded
draught at 24 feet, we have a displacement of about
9800 tons, which it will be observed leaves a margin of
strength of 3313 tons, sufficient for all practical purposes
as regards the durability and safety of the ship.

We could multiply these calculations to any extent, but
I only wish to point out for the guidance of engineers
what we consider the best and most effective principle of
construction to ensure a powerful resistance to strain, and

T 2

276 IRON SHIPBUILDINa

a distribution of material capable of withstanding the
shocks of a rolling sea> or any other trials to which in ex-
treme cases the vessel might be exposed.

Water-tight bulkheads are of great importance in the
class of vessels we are now considering. These not only
bind the sides of the ships together from the keel to the
deck, but they give rigidity and strength to the whole
structure^ and there is no part more deserving of attention
in large ships than these bulkheads. In a ship of 500 feet
length and 68 feet beam^ it might be desirable to divide her
into two parts by a longitudinal bulkhead up to the middle
deck. That would, however, be inconvenient in many
. cases in both sailing vessels and steamers. In fact, in the
latter it would be inadmissible on account of her machinery;
we must therefore deal with the construction under those
conditions required by the service for which she is intended.
This does not, however, affect the general principle that
bulkheads made perfectly water-tight and stiffened with
angle and T-iron should form component parts of the
structure, and require great attention both as to the num^
ber of compartments and the position in which they are
placed.

It now remains for consideration in detail whether the
principle of longitudinal keelsons, with corresponding plate
and cellular stringers, is or is not superior to the ordinary
construction with transverse frames. In vessels of such
immense tonnage, it would appear from the formula applied
to hollow girders that a great increase of transverse
strength may be gained, as in the case of smaller vessels,
previously considered. In a vessel floating on water the
force of external pressure at a depth of 24 feet is about
1572 lbs. per squafe foot, or 11 lbs. per square inch, and
this distributed over the surface of one of the cells, 6 feet
by 4 feet, amounts to 17 tons nearly, or is equivalent to a
force of 8i tons at the centre of the cell at midships. Now

THE CELLULAR SYSTEM,

277

this would be too great a pressure for a |-Incli plate, and
would cause a bulging inwards, were it not for the counter-
poising pressure on the adjoining cells, which has a ten-
dency to neutralise the bulging tendency by straining the
metal uniformly over the keelsons and transverse ribs. In
order, however, to increase the rigidity of these parts, it
will probably be necessary to run down the middle of each
cell bars of T-iron 6 ins. by 5 ins. as shown at g, fig. 68, in

Fig 58.

f^-'-^^^'^-'-'^^i ,

the line of the keelsons b J, composed of angle irons and
vertical plates riveted to the sheathing plates 3 feet wide
and 12 feet long. On this principle the T-iron would also
rest upon the longitudinal plated, and the transverse joints
would be covered by the plates, shown at c c, fig. 59, placed
under the frames and chain-riveted. The covering plate in
this case being thicker than the sheathing plates, in order
to compensate for an increased number of perforations for
rivets along the line of the joint

It has been stated that it would be necessary to have an
increased number of transverse frames in order to bring
the lines of the vessel into shape ; should this prove correct,
another light rib may be used, shown at e e, in the plan,
fig. 59, riveted to the sheathing on the same principle as
the other ribs ffff, which are four feet asunder. These

T 3

278

IRON SHIPBUILDING.

practical details, however, we may leave to thie judgment
of the builder, as not essential to the stability of the ship.
In this way the resistance of the cells to bulging would
be more than doubled, and the whole of the cellular con-
struction rendered secure under every form and condition
of strain. The preceding sketch (fig. 58) represents the
sectional form of the cells, each of which may be stiffened
by gussets, a a and d d, riveted to the angle iron of the
keelsons and transverse frames. Fig. 59 shows in plan
the keelsons, b 6, Tihs^ff, additional rib, e e, T-iron along
the bottom, a a, and covering plates, c c, chain-riveted.
On this plan the cells would be open from one bulkhead
to the other, and with proper water-tight manholes be-
tween each bulkhead might, if necessary, be used for
stowage or for the insertion of tanks in which fresh water
might be kept ready for use.

Fig. 59.

o o
o o

Q O

^ j^ o o o o o o o

ooooo
o o

9 .<?

On the above* construction the sheathing plates would
be lap-jointed, using thfe keelson angle irons and the inter-
mediate T-irons as stiffeners for the cells, as shown in fig.

THE CELLULAB SYSTEM.

27d

60,"^hlcli represents one half of the cellular system at the
bottom of a vessel from the keel to the turn of the bilge.

Enlarged covering plates^ chain-riveted, for the trans-
verse joints, are of great importance both in regard to the
lateral and longitudinal strength of the ship. The resist-
ance to tension would be one-sixth greater than with the
ordinary construction, and thus the security of the ship
would be greatly increased.

As regards the upper and intermediate decks, there
would be no change except the introduction of two cells.

Fig. 60.

one on each side of the hatchways, and four other cells,
two on each side of the ship, as shown in fig. 56. In the
sectional area of the upper deck it will be observed that
in the previous calculation we allowed about -J^th as the
value of the deck planking in resisting a compressive or
tensile strain, and that we made a further allowance of
material to the bottom to compensate for the wear and
tear of those parts. Hence, the sectional area of iron in
the upper deck will be to that in the bottom in the ratio
of 4 to 6. These proportions have been assumed, but they
are in accordance with experimental researches, or at least
so far as we have results bearing on this question ; and it

T 4

280 IBON SHIPBUILDING.

only requires an extension of such experimental investi-
gations to prove how far these proportions approximate to
the correct ratio for resisting the strains at those parts
respectively.

A series of well-conducted experiments of this kind are
much wanted, and a government grant of lOOOZ., with a
similar grant from Lloyds and from the shipowners' fund,
would set the question at rest, and establish in ship-
building, as in other constructions, true principles, the cor-
rect expression of physical laws. It is with the object of
aiding in the attainment of this that I have ventured to make
these suggestions. The subject is one of deep importance
to the community, one on which we are very deficient in
knowledge, and one which will reward investigation, and
that with great benefit to the public and to mechanical
science, and without injury to existing interests.

Impressed with the conviction that we are still labouring
under difiiculties from a want of knowledge of the true
principles of naval construction, we are encouraged from
other movements in looking forward to the time when these
diflSculties will be removed, and when greater economy in
the distribution of the material will be accomplished,
from the reduction of the whole system of shipbuilding to
the exact laws of science.

In the discussion of this question I have not ventured
to inquire into the applicability of the cellular construction
to ships of war, and my reason for the omission has been
that the effect of shot upon iron ships has yet to be decided
upon. I am aware that the Admiralty some years since
came to a conclusion adverse to the use of iron, which I
am not now prepared to call in question. But the im-
proved condition of our iron constructions, and the in-
creased tenacity of the material, taken in connection with
our improved system of gunnery, may afford reasons for

WAR VESSELS. 281

altering that decision^ and lead to results favourable to the
use of iron as a material for building vessels of war.

With the Whitworth rifled gun, for example, with an
oblong fiat-ended missile, iron is penetrated by a process
that drills or cuts out the core without splintering or
tearing up the surrounding surface, and looking forward
to still further improvements, the iron ship may be in-
creased with safety under the influence of a more destruc-
tive arm than has heretofore been used. Be this as it
may, the same principles of construction will apply to the
navy as to the vessels of the merchant service ; and till it
it has been more conclusively proved that iron is in-
applicable to the construction of ships for the purposes of
war, we may reasonably conclude that this material may
ultimately become the best safeguard of Her Majesty's
dominions at home and abroad.

[Since the above was written I have deemed it neces-
sary to insert in the Appendix two letters addressed to
the editor of the " Times," bearing directly on the defect-
ive construction of iron ships. These letters were written
after the loss of the Royal Charter by a near and dear
relative, and are so much to the purpose, that I should
consider myself wanting in duty if I omitted statements
of such importance to the public. I have also given a
quotation from a recent lecture of Mr. Grantham's, in
which he shows with great clearness some of the causes of
weakness in our present construction, having arrived, in-
dependently, at nearly the same conclusions as myself on
the necessity for a large increase of transverse strength.]

282

LECTURE VIL

ON WROUGHT IRON TUBULAR CRANES*

These structures are identical in principle with the tu-
bular bridges over the Conway and Menai Straits, and
present additional examples of the advantages which may
yet be derived from a judicious combination of wrought
iron plates in constructions requiring security, rigidity,
and great strength.

About ten years ago the first design for a wrought
iron crane was submitted to the Admiralty for their ap-
proval. It was a crane calculated to afford greater secu-
rity and facility in the embarkation and disembarkation of
heavy stores, and was in other respects better qualified fot
raising heavy weights than the cranes previously in use.
The design was placed in the hands of the Surveyor of the
Navy and Mr. Lloyd the Inspector of Machinery, who
were so well satisfied as to the superiority of the construc-
tion that an order was given to erect six of them, in dif-
ferent positions along the line of quays of the new docks
at Keyham and Devonport.

These cranes were all of the same size and strength, and
were intended to lift weights of 12 tons to a height of 30
feet above the ground, and to sweep them round over a
circle of 65 feet in diameter; so that the projection of the
jib was 32 feet 6 inches from the centre of the stem, and
the extreme height 30 feet above the working platform.

PRINCIPLE OP CONSTRUCTION. 283

The cranes were composed of wrought iron plates riveted
together, and so arranged as to give the back or convex
side an adequate degree of strength to resist tension, and
the front or concave side, which in these cranes was of
the cellular construction, a corresponding power to resist
compression. The form was similar to that of the pro-
longed vertebrae of the bird, from which the machine
takes its name ; it was truly the neck of the crane, taper-
ing from the point of the jib, where it was 2 feet deep by
18 inches wide, to the level of the ground, where it was
5 feet deep and 3 feet 6 inches wide. From this point it
again tapered to a depth of 18 feet below the surface,
where it terminated in a cast-iron shoe, forming the toe on
which the crane revolved.

The lower or concave side, which had to resist a force of
compression, consisted of plates forming three cells, vary-
ing in width in the ratio of the strain at each part ; and
on the other hand the convex or top side, which has to
bear the pull or tension due to the suspended weight, was
formed of long plates connected together by the system of
" chain-riveting," first applied in the tubular bridges in
Wales. The sides were of uniform thickness throughout,
the joints being covered with T-iron internally, and on
the outside by strips 4^ inches wide.

The form of the jib is shown in fig. 61, with a portion
of the side removed from a to the foot, in order to show
the cast-iron cylinders built into the masonry ; and the
rollers which encircle the body of the crane and support
the jib vertically, permitting, however, free motion of revo-
lution as they roll against the large circular plate a a.
Immediately above the rollers is a platform a, 12 feet in
diameter, attached to the jib, on which the men stand to
work the crane ; b is one of the winches connected by
gearing with the barrel in the interior of the crane, on

TUBULAB CRANES.

THE KEYHAM CBANES. 285

which the chain is coiled, and d a wheel connected by
gearing with a spur segment wheel fixed on the masonry^
by which the crane may be revolved in any direction at
pleasure.

Fig. 62 is a plan of the crane and platform^ showing
the upper flanch of the large ring a a, with the holding
down bolts ccc. Fig. 63 is a section of the jib of the
crane^ showing the cells on the concave side of the jib.

As this was an entirely new construction, it was consi-
dered desirable to test its powers of resistance to strain,
and to determine by direct experiment the law of strength
which it followed. To accomplish this, each of the cranes
was loaded progressively with weights up to 20 tons,
the deflections being carefully recorded as the experiment
proceeded.

No. 1 Crane, Nov. 8 th, 1850. — With 5 tons suspended
the crane was turned completely round without any alter-
ation in the deflection. With 10 tons suspended the crane
was again turned round, and in 8 minutes the deflection
increased from 1'70 inch to 1*85 inch, at which it remained
after sustaining the load during the whole of the night, a
period of about 1 6 hours. The next day the experiments were
resumed ; and on turning the crane round with a load of 20
tons, there was no perceptible alteration in the deflection,
and the permanent set after removing the load was '64 inch.
Hence the deflection was 3'33 inches for a load of 20 tons.
The ultimate strength of the crane is therefore much
greater than is requisite in either theory or practice ; and
although tested with nearly double its intended load, this
was still far short of its ultimate power of resistance,
which by calculation is five times greater than its nominal
power.

No. 2 Crane, Oct. 8th, 1851.— With 5 tons suspended
the crane was turned completely round without any

286 TUBULAR CRANES.

perceptible change in the deflection. With 10 tons sus-
pended the crane was again turned round, when the
deflection increased from 1'68 inch to 1*87 inch; on
removing the load the permanent set was found to be '25
inch, being the amount of loss of elasticity due to a load
of 10 tons suspended from the extreme point of the jib.
With 15 tons suspended the crane was turned round
with an increase in the deflection of only '06 inch. Pre-
vious to removing the final weight of 20 tons the orane
was turned round, in order to test the efficiency of the
movable parts, and also the break wheel, which at this
trial was used for lowering the load. On removing the
weights, it was ascertained that the retaining powers of
the riveted joints and the elasticity of the parts in com-
bination exhibited rather more tenacity than in the first
crane that was made, as the jib when relieved from the
load of 20 tons rose to within '62 inch of its original
position.

No. 3 Crane, Jan. 7th, 1852. — In this and the suc-
ceeding experiments the cranes exhibit still greater powers
of resistance as regards the strength or ultimate deflection
of the jib. The defects of elasticity are also diminished to
an extent which clearly shows that the workmen had
become more expert and probably more careful in the fit-
ting and riveting of the parts.

In turning round the crane No. 3, the deflection re-
mained unaltered with 5 and 15 tons load, but increased
10 inch with 10 tons load. On removing the load of
20 tons the permanent set was found to be only -40 inch,
which gives 3*16 inches as the deflection due to the load
of 20 tons.

No. 4 Crane, Feb. 4th, 1852. — The results of the ex-
periments on this crane correspond closely with those
enumerated for No. 3. The same indications of strength.

THE KEYHAM CHAJTES. 287

elasticity, and deflection follow each other with remark-
able precision. No alteration in deflection took place
when the crane was turned round with loads of 5, 10, and
15 tons. The crane was turned round with the load of
20 tons, when the pennanent set was found to be '62 inch,
making the deflection 2*94 inches for the load of 20 tons.

No. 5 Crane, Feb. 6th, 1852. — This crane was sub-
jected to the same treatment with nearly the same results.
In turning it round with 5, 10, and 20 tons load the
deflection remained the same ; with 15 tons load the de-
flection increased '05 inch in turning round. On removing
the load of 20 tons, the permament set was '44 inch,
giving a deflection of 3*18 inches due to the load of
20 tons.

No. 6 Crane, Feb. 14th, 1852. — In turning round with
5 tons load the deflection increased '07 inch; but with
10, 15, and 20 tons load no change took place in turning
round. On removing the load of 20 tons, the permanent
set was '50 inch, giving a deflection of 3*25 inches for the
load of 20 tons.

In the above experimental tests, it is satisfactory to
obsierve that the resisting powers of this construction are
limited only by the weight of the foundations and the
strength of the chains, wheels, and machinery for lifting
the load. A crane of 12 tons has a stem and jib capable
of supporting 60 tons, or five times the load it is intended
to bear, a much greater margin than is generally allowed
for constructions of this kind.

The following Tables give a summary of the results of
the experiments on the twelve ton cranes at Key ham.

288

TUBULAR CBANE9.

Table l.--- Deflections of Tubular Wrought Iron Cranes.

Load at end of Jib.

Deflection at the end of Jib.

No. 1.

No. 2.

No. 3.

No. 4.

No. 5.

No. 6.

Ton*.

Inf.

Ins.

•32

•31

•37

•25

•27

•31

•50

•60

•65

•62

•90

•87

•75

•88

•82

— turned round

•90

•87

•75

•88

•89

105

1-06

1-20

118

1-35

1-37

•

1-50

1-70

1-68

1-70

1-62

1*62

1-76

— turned round

1-85

1-87

1-80

1-62

P76

205

2*22

219

2-40

2*40

2-60

2*62

2 80

2-80

2-69

2-56

2-63

2-31

— turned round

2-80

2-86

2*69

2-56

2-68

2-31

3-00

3 00

3-20

3-31

3-50

373

3-69

■•

3-97

3-92

3-56

3-62

3*75

— turned round

3-97

3-92

3-56

3*62

3-75

Table IL — Summary of Results,

Number of Crane.

Deflection at Point of Jib
Hich ao tons load.

Permanent set with
ao tons load.

No. 1.
No. 2.
No. 3.
No. 4.
No. 5.
No. 6.

Average

Ins.

3-97

3*92

3-56

3-62

3-75

In.
•64
•62
•40
•62
•44
•50

3-73

•54

ADVANTAGES.

289

The average permanent set being deducted from the
average final deflection leaves 3*19 inches as the average
deflection for a load of 20 tons, which is at the rate of
*16 inch per ton. These experiments present a remark-
able consistency and uniformity in the strength and elas*
ticity of the material under strain ; and it will be observed
that the permanent set, varying from *40 inch to *64 inch,
is small in amount when compared with the load and the
peculiar nature of the strain to which the jib was sub-
jected.

Fig. 64.

Pig. 65.

Fig. 66.

In the construction of cranes, whether of wood or iron,
it has been the usual custom to place the jib in an inclined
position at an angle of about 40^ or 45^ with the stem, as
in figs. 64 and 65, so as to obtain the greatest strength ; in
this position the extreme point from which the load is sus-
pended has to be stayed or held in its place by oblique or
horizontal tie rods. With this arrangement it will be
observed that, if the article to be raised be at all bulky,
such as a large bale of merchandise or a marine boiler, it
will be prevented from being elevated to the top of the
crane by coming in contact with the diagonal stay or jib.
Hence with ordinary cranes a considerable part of the
height is practically unavailable. In the wrought iron
crane, however, fig. 66, this defect is obviated, since the

290 TUBULAR CRANES.

curvature of the jib is suf&cient to allow the article to be
raised to the highest point to which the chain ascends.

The advantages peculiar to this construction of crane
are its great security and the facility with which bulky
and heavy bodies can be raised to the very top of the jib
without the least risk of failure. It moreover exhibits,
when heavily loaded^ the same restorative principle of elas-
ticity as is BO strikingly exemplified in the wrought iron
tubular girders. These constructions^ although different
in form, are nevertheless the same in principle, and un-
doubtedly follow the same law as regards elasticity and
power to resist fracture.

Several cranes of the same power and construction have
lately been erected at Keyham, Devonport, Birkenhead,
and Southampton, and at St. Petersburgh, all of which
have been severely tested by the suspension of weights
considerably greater than they were intended to bear.
Ten ton and three ton cranes have been experimented
upon in a similar manner and attended with the same
results ; all of them exhibiting great powers of resistance,
greatly increased convenience for raising the load under
the curvature of the jib, and equal facility in moving the
crane to any point within reach of the sweep.

Subsequently to the erection of these, the first cranes
on the tubular system, a number of others followed of dif-
ferent dimensions, and for various purposes, all of which
exhibited the same powers of resistance and other advan-
tages. It is, however, due to the Government to state
that they took the initiative in the introduction of this
new system, and finding the twelve ton cranes to work to
their entire satisfaction, they ordered two more for Devon-
port, and a colossal crane, to lift 60 tons, for Keyham.
These, and many others of smaller and larger sizes, have
since been erected upon the same principle, the only change
in their construction of importance being the abandonment

COLOSSAL CBANE. 291

of the cells In all but the largest^ and the substitution
of strong T iron ribs in their place, by which sufficient
strength is secured with greater facility and economy.
They have also been adapted for railway travelling
' cranes, and in many cases have had an engine and boiler
attached to the platform, so as to work them by steam.

The colossal 60 ton crane at Keyham consists of a rect-
angular wrought iron tube, curved to a radius of about
46 feet, and tapering uniformly from 9 feet deep by 5 feet
6 inches wide at the level of the ground, where from the
leverage of the crane the strain is the greatest, to 3 feet
6 inches deep by 2 feet wide at the point of the jib. From
the level of the platform it is also tapered downwards to
about 1 foot 8 inches square at 23 feet below the level of
the ground, where it fits into a cast iron shoe working in
a socket or step on which the crane revolves. The point
of the jib is 60 feet above the level of the platform, and
sweeps a circle of 53 feet radius ; so that it will lift the
heaviest load perpendicularly from a mean distance of
37 feet from the quay wall, and to a height of no less than
85 feet above low water markj and land it at 69 feet from
the edge of the quay.

The crane itself is built on precisely the same principle
as the tubular bridge, and may indeed be considered as a
curved tubular girder inverted, the top side being the
front or concave side of the crane, and the bottom side
forming the convex or back part of the structure. Hence
it may be described as composed of back plates, side plates,
and cell plates.

The back plates, which correspond with the bottom plates
of a tubular girder, have to resist a strain of tension, are
made as long as possible to avoid joints, and are care-
fully chain riveted. They are |^ inch thick, and each half
the width of the crane ; and taking those on one side and
beginning at the bottom of the well, the first plate is

u 2

•292 TUBCLAB CBAKES.

13 feet 9 inches long; the secondj which passes the point
where the downward taper ends and the upward begins, is
13 feet 6 inches long; the next is 12 feet 6 inches, fol-
lowed by six others, each 12 feet long, and these again
terminated by a plate 15 feet long, which curves round
over the pulley at the extreme point of the jib. These
plates are covered externally by a long strip 8 inches
broad and ^ inch thick, extending the entire length of the
crane and covering the longitudinal joint between the
back platea The cross joints are placed alternately, and
at each side of the crane there is a line of angle iron con-
necting the back plates with the side plates. So that the
sectional area of the back of the crane subjected to ten-
sion is

At the bottom. . . . 10*50 square inches.

At the pUtfonn • . , 27*75 „

At the point of the jib . • . 12*00 ^

The sides of the girder are formed of plates 3 feet broad
at the outer edge or back of the crane, riveted together
with T iron 4 x 2 x -| inches at every joint inside, and a
strip outside, to give the necessary rigidity. Beginning
at the toe, the first three plates are ^ inch thick ; the next
three -^ inch thick ; the next five, which have to resist
the horizontal thrust against the cast iron circle at the top
edge of the well, ^ inch thick ; and the remainder -^ inch
thick.

The front of this crane is constructed with four cells, to
resist the immense compressive strain to which that part
is subjected. The two series of plates which form the
front and back of the cells, are composed of plates varying
from 5 feet to 7 feet 6 inches long, and ^ inch thick.
Each of these plates is riveted to the side plates by two
angle irons. The space between them is divided into four
cells by three vertical plates parallel to the side plates^ and

COLOSSAL CBAKE. 293

eight angle irons at the corners fiirther strengthen the
structure thus formed. The reason of this arrangement
is that wrought iron plates from their flexibility offer but
a small resistance to compression in the direction of their
thickness^ as they bend or buckle with a comparatively
small force. The five vertical plates, however, which
form the sides of the cells, are placed in the position in
which they offer a maximum resistance to compression,
namely with their width or depth in the direction of the
strain ; and the angle irons and the plates E and F serve
to keep them in position and give great rigidity to the
structure. The centre plate of the cells is ^ inch thick,
and the two remaining plates each -^ inch thick. The
sectional area of the concave or front part of the crane
subjected to compression is therefore

At the platform . . . 62*58 square inches.

At the point of the jih . . • 34*83 „

Attached to the back of the crane is a tail piece or box
of wrought iron, contsdning cast iron weights acting as a
counterpoise to the jib. The chain is attached to the crane
by a bolt and nut at the point of the jib, and passes round
four pulleys, two moveable and two fixed, in the end of
the jib ; it is then conducted down in the interior of the
jib over three rollers to the barrel, which is also in the
tube near the ground. On each side of the crane a strong
cast iron frame is fixed for receiving the axles of the spur
wheels and pinions. Four men, each working a winch of
18 inches radius, act by two 6 inch pinions upon a wheel
5 feet 3f inches diameter; this in its turn moves the spur
wheel, 6 feet 8 inches diameter, by means of an S inch
pinion, and on the axle of the former the chain barreli
2 feet in diameter, is fixed. Hence the advantage gained
by the gearing will be

W 18 X 63-75 X 80

P 6 X 8 X 12

158

294 TUBULAR CBANES.

or taking the number of cogs in each wheel

W 18 X 95 X 100

F 12x9x10

» 158;

and as this result is quadrupled by the fixed and moveable
pulleys^ the power of the men applied to the handles is
multiplied 632 times by the gearing and blocks. A break
wheel, 5 feet 2 inches diameter, is fixed on the other end
of the spindle of the spur wheel ; and the power applied
at its circumference is accordingly multiplied about 100
times by the gearing and blocks.

At the level of the ground the crane Is firmly fixed in a
strong cast iron frame, the outer edge of which is a circle
of 1 1 feet 3 inches diameter ; and on the edge of the well
a similar ring is embedded in the masonry and secured by
long holding-down bolts, leaving a space of 10 inches all
round between it and the inner ring. In this space a
number of strong cast iron rollers are placed, 10 inches in
diameter, to prevent friction and facilitate the movement
of the crane as it revolves round its axis. Upon the cast
iron ring on the quay wall is fixed a circular rack, com-
posed of cogged segments bolted together, into the teeth
of which a pinion works, whereby the crane is made to
revolve. This pinion is worked by a worm and wheel
placed in the counterpoise box; and two men are suf-
ficient to move round the crane with 60 tons suspended
from the extreme point of the jib. In working the crane
the men stand upon a cast iron platform attached to it a
few inches above the level of the ground.

This crane, taking it altogether in regard to its strength,
height, and the extent to which the weight raised can be
swung round, is probably one of the first and most
powerful in Europe. It can raise or lower boilers in and
out of the holds of ships of the line ; pick up the heaviest
ordnance from any of the decks ; and ship or unship masts

STEAM CBANES. 395 I

with tlie same or greater ease fhaa is now done hy tlie
large sheara used for that purpose in any of tbe dockyards.
In fact a colossal crane of this description, 120 feet high,
was submitted to the surveyor of the navy as a substitute
for the large masting shears at Woolwich, which were
worn out, but owing to some other arrangement the
project was not carried into effect.

Fig. 67.

Since the erection of the 60 ton crane at Keyham, a
steam engine has been fixed upon tbe counterpoise plat-
form, which renders it independent of manual labour, and

296 TUBULAB CRAKES.

gives greater facility and despatch in raising heavy
vreighta. A crane of the same size as this has since been
erected at Portsmouth dockyard, and has also an engine
and boiler attached to the platform behind the crane, so
that if occa«on require it can be worked hy steam. The
engines consist of two seven inch cyUnders with link
motions, similar to those of a locomotive, by which they
can be stopped or reversed with the greatest ease.

Fif.68.

Fig. 67 is a general view of a ten ton crane on the same
principle, with its en^ne and boiler attached. This crane
sweeps a circle of 50 feet in diameter, and lifts to a height
of 26 feet above the platfomi. The cylinders of the engine
are 6 inches in diameter, to obtain a rapid elevation of the
weight, and have link motions and reversing gear, as in

BAILWAY TRAVELLING CBANES. 297

the larger cranes. If necessary they may be at once dis-
connected^ and the cranes worked by hand.

The tubular principle has also been applied to railway
travelling cranes^ as shown in fig. 68, which is a sectional
elevation of a 15 ton crane upon its truck. This crane
revolves upon a steel pivot at p^ and is balanced by a
weight of about 8 or 10 tons attached behind the jib at
w. In other respects it is precisely similar in construc-
tion to the stationary cranes previously described. It
sweeps over a circle of 25 feet in diameter^ and lifts to a
height of 18 feet above the rails. The chain barrel is
protected from the weather within the jib, as shown at a»

From the above description it will be seen that the
great advantages of these constructions is their extreme
lightness as compared with the weights they have to lift,
and their powers of being extended to any amount of
strength^ height^ or sweep that may be wanted. In con-
clusion^ they are admirably adapted for the loading and
discharge of cargoes from vessels in dock^ and for the
transfer of the load to any point within the limits of a
circle described by the chain suspended from the jib.

298

LECTURE VIII.

ON THE PROPERTIES OF STEAM, ITS MANAGEMENT

AND APPLICATION.

[Delivered before the Leeds Philosophical Society. March I860.]

If we were to enter upon the statistics of the accidents
which have arisen from the use, or rather the abuse of
steam, we should have to present a fearful catalogue of
catastrophes and loss of life. Few people are fully aware
of the suffering which these accidents have entailed upon
a certain class in the community, or of the immense de-
struction of property which has proceeded from the mis-
directed employment of steam.

The Great Author of Nature has supplied us with a
power which property applied changes the destinies of
nations, and confers unheard of benefits upon the human
race. We have it at command in every department of
human effort, and in every condition of life it subserves
our will through every gradation from one to a thousand
horses power. It stems the tides and currents of the
ocean. It ploughs, spins, weaves, and grinds our corn.
It drains mines, pumps water, and carries us across the
country with a celerity unknown in the past, and with
a despatch and power which would have set at defiance the
Genie of the Arabian Nights. It only requires a careful
and judicious treatment, in preserving it from excesses of
heat and cold, and confining it within bounds sufficiently
strong to retain it, and a wise direction of its efforts,
founded upon a clear and accurate knowledge of its pro-
perties.

ON STEAM BOILER FLUES. 299

When we look around us and count the number of
eteam engines at work in every city, town, and hamlet ;
when we see them traverse the rail, and depart across the
ocean with unerring certainty, and consider at the same
time the necessity of having all these movements under
safe control, it assuredly follows that the makers of these
engines and those who employ them should bring to their
construction and superintendence a large degree of intel-
ligence and a full knowledge of their principles. Unfor-
tunately this is not always the case ; we are still deficient
of knowledge on many points of construction and in
regard to many of the properties of steam. To supply
part of that knowledge is the object of the present address,
in which I hope to show some of the means by which
steam boilers may be made more secure, and to correct
some erroneous views which have obtained currency in
regard to the properties of steam.

I. NEW PRINCIPLES IN THE CONSTRUCTION OP BOILERS.

The production of steam in a vessel placed over a fire
is a simple and well-known process, and one which requires
no comment. The form of the vessel, commonly called the
boiler, when steam is to be produced for industrial purposes,
is, however, an important consideration, both as regards
economy and strength. In the history of the steam engine
we find an immense number of forms of boilers, most of them
having served the purposes for which they were intended.
At first, when high pressure steam was scarcely known,
great strength was not required, and the form of the boiler
was not of so great importance as at present. At that time
the supply of water was regulated by a float, and the pres-
sure in the boiler seldom exceeded 10 or 12 lbs. per square
inch. At this pressure the waggon-shaped boiler and other
forms with flat surfaces were not so objectionable; but when
steam is employed at from five to fifteen times this pres*

300 ON STEAM

sure, it becomes a qaestion of the highest importance that
the vessels to retain such an immense force should be con-
structed of the best material, duly proportioned in thick-
ness, and arranged in the form of maximum strength.

In former lectures I have discussed the rules and pro-
portions for the construction of boilers adapted for station-
ary engines, especially in reference to the resisting powers
of the outer shell. At the time that those proportions
were given we were not aware of a hidden source of weak-
ness, which further investigation has discovered, and which
we now propose to remedy by simple means, which have
been suggested by an increased knowledge of the laws of
construction.

It is well known that the great majority of the boilers
in this country are now constructed with internal flues or

Fig. 69.

tubes traversing the whole length of the boiler, most of
them being upwards of thirty feet long, and varying from
two to three feet in diameter. These flues are generally
composed of plates of the same thickness as the outer shell
of the boiler, and being of cylindrical form, they have
been considered hitherto much stronger in their powers of
resistance when forming an arch opposed to a uniform
external pressure, than the outer shell subjected to the
same force acting from the interior. This opinion was
acted upon with confident security until its erroneousness
was shown by direct experiment. Fig, 69 shows the ordi-

BOILER FLUES. . 301

nary form of the boiler in the manufacturing districts^
about 30 feet in lengthy 7 feet in diameter^ with two in-
ternal flues a a, about 2 feet 8 inches in diameter. These
flues as well as the external shell are generally composed of
1^ inch plates, which corresponds with a bursting pressure
for the outer shell of 303^ lbs. per square inch, which of
course ought at the same time to be the collapsing pres-
sure of the flues. This unfortunately is not the case, as,
according to experiment, it is now found that the flues
would give way with about 100 lbs. pressure per square
inch, or the boiler would be destroyed by collapse at one-
third of the bursting pressure of the shell. It is evident
then that these internal flues have been constructed a
great deal too weak, and without a knowledge of the true
law of collapse.

It has long been a desideratum to obtain some law by
which the engineer could proportion the strength of the
internal flues. There have been no definite rules to guide
us hitherto in proportioning the diameter, length, and
thickness of plates of the flues, so as to correspond with
the strength required in the boiler. And even in cases
where explosions have taken place from collapse, we have,
it is to be feared, too often mistaken the actual cause,
from the quantity of the debris covering the site, and the
force which has torn to pieces the outer shell.

To supply this want I undertook some time ago a long
series of experiments on the laws of collapse, the results of
which were made public through the Transactions of the
Royal Society.* The chief laws which were ascertained
may be stated as follows : —

I. Strength as affected by length. — The results under
this head are singularly interesting and conclusive.

* The two papers on this subject are reprinted in the present volume,
pp. 1—45 and 74—92. In this Lecture the results are exhibited in a more
popular form for practical readers.

302 ON STEAM

"VVithin the limits of from 1*5 foot to about 10 feet in
lengthy it is found that the strength of tubes simitar in
other respects and supported at the ends by rigid rings
varies inversely as the length.

Thus taking the 4-inch tubes of different lengths, we
have the following mean results derived from experi-
ment : —

1. Resistance offourAnch tubes to collapse.

Diameter Thickness of Length

ins. plates, ins. ins.

(D.) (t.) (L.)

4 '043 19

4 043 60

4 -043 40

The remarkable differences which exist in the resistinoj
powers of the above tubes will be at once apparent. The
constancy in the numbers in the last column, which re-*
presents the resisting powers of the tubes reduced to unity
of length, on the assumption that the strength varies in-
versely as the length between the supported ends, is a
proof of the substantial accuracy of the above law.

2. Resistance of six-inch tubes to collapse.

Collapsing

pressure in lbs.

(P.)

P.L.

137

2603

2580

2600

D.
6

t.
•043

L.
30

P.
55

P.L.
1650

•043

1888

In this case, as before, the product of the collapsing
pressure by the length is constant, and verifies the law,

3. Resistance of eight-inch tubes to collapse*

t. L. P. P.L.
'043 39 32 1248

•043 30 89 1170

Resistance of ten-inch tubes to collapse.

D.
10

t. L. p. P.L.
•043 50 19 950

043 30 33 990

BOILER TLUES. 303

In the same manner all the experiments might be taken
and compared, and the law found true in every case. The
discrepancies are comparatively small, and, as they appear
to follow no law, are evidently errors of observation arising
from unavoidable defects in the construction of the tubes
and the varying rigidity in the plates of iron.

Two experiments made upon actual boiler flues fixed in
their proper position in boilers show that there is no great
departure from the same law up to 35 feet in length.

5. Resistance of boiler Jlues to collapse.

D. t. L. p. P.L.

•375

3395

•375

127

3175

The longer of these two flues collapsed with 97 lbs. per
square inch, whilst the shorter sustained 127 before giving
way.

II. Strength as affected hy Diameter.

A precisely similar law is found to prevail in relation to
the diameter. Tubes, similar in other respects, vary in
strength inversely as their diameters. Testing this law
in the same manner as the last, we have the following
table: —

6. Resistance to collapse of Jive-feet tubes.

D.
4

t.
•043

L.
60

P.
430

P.D.
172

•043

320

192

•043

20-8

176

•043

160

•043

12-5

150

The nearly constant numbers given in the last column,
and representing the product of the diameter and collaps-
ing pressure, or the collapsing pressure reduced to unity
of diameter, verify the above law of strength.

304 OK 8TEAM

7. Resistance to collapse of two feet six inch tubes.

D. t. L. p. P.D.
4 '043 so 84 336

6 *043 SO 52 312

8 -043 30 39 312

10 "043 30 33 330

12 -043 30 22 264

The numbers in the last column are nearly constant.

Ill, Strength as affected by thickness of Plates.

It is found that the tubes vary in strength according to
a certain power of the thickness^ the index of which,
taken from the mean of the experiments, is 2*19, or rather
higher than the square.

P- 806300 x^^ . . . (I).

Where L is in feet. Or for convenience of calculation,

log. F - 1-5265 + 2*19 log. 100 t-log. (LD) . . . (2).

With regard to cylindrical flues, the experiments indi-
cate the necessity of an important modification of the
ordinary mode of construction, in order to render them
secure at the high pressures to which they are now almost
constantly subjected. The weakness of flues on the
present construction has already been shown. To remedy
this defect, it is proposed that strong rigid rings of T, or
angle iron, should be riveted at intervals along the flue,
thus practically reducing its length, or in other words
increasing its strength to uniformity with that of the
exterior shell of the boiler. This modification, which is
represented in Plate II. figs. 2 and 3, is so simple and yet
so effective, that its adoption may be confidently recom-
mended to the attention of those interested in the con-
struction of boilers.

BOILER FLUES.

305

The following table of the proportions of boiler flues,
supplementary to those given in the first series of Lectures
on the proportions of the external shell, will be found
worthy of attention.

Table showing the proportions of internal Boiler Flues,
for resisting a collapsing pressure of 450 lbs. per square
inch*

Diameter of
Flue in ins.

Collapsing Pressure
in lbs. per sq. in.

Tliickness of Plates In parts of an inch.

For a Flue
10 feet long.

For a Flue
20 feet long.

For a Flue
30 feet long.

13
18
24
30
36
42
43

450

•291
•350
•399
•442
•480
•516
•548

•399
•480
•548
•607
•659
•707
•752

•480
•578
•659
•730
•794
•851
•905

In the above table the length of the flue must be
measured between the rigid supports. In an unsupported
flue, as ordinarily constructed, the length is measured
between the end plates of the boiler ; in a flue as pro-
posed above between the T iron ribs. For a collapsing
pressure of 450 lbs. the safe working pressure would be
75 lbs. per square inch.

It will not be necessary to remark further on this sub-
ject, except to illustrate, by an example, the importance of
these facts to the safety of the public. In the disastrous
accident which attended the first trial trip of the Great
Eastern the funnel of the boilers, which was surrounded
by a water-jacket, gave way by collapse at what was pro-
bably a comparatively low pressure. This might easily
have been prevented had the maker been aware of the.

* This table was given in the tliird edition of the first series of " Useful
Information.*'

306

ON THE PBOPEBTIES OF STEAM.

Fig. 70.

extreme weakness of such flues when of large diameter
and great length.

Fig. 70 shows the general arrangement of the boilers
and funnel, covered by the jacket a a. The funnel, six

feet in diameter, is in this case exposed to
the pressure of the steam, together with
that of a column of water nearly forty feet
in depth, and these two forces were quite
sufficient to collapse the funnel and cause
the frightful explosion which occurred.

The great weakness of elliptical tubes,
shown in the experiments on collapse, points
out another source of danger in marine
boilers, viz. the " take-up ; " that is, the
drawing in of the plates from a rectangular
to a cylindrical form, where the flues join
the funneL This part requires the utmost
attention, as it is not only the weakest part
of the boiler from its form, unless very
carefully stayed, but it is much exposed to
overheating from the gases rising from the
furnaces where it is above the level of the
water, in which case its powers of resist-
ance must be greatly diminished.

II. THE DENSITY OF STEAM.

If fatal accidents in the use of steam lead us to study
the forms and proportions of boilers, the necessity for
economy in its production and application should induce us
to study minutely its properties. The knowledge of the
latent heat of steam, the discovery of which had been
made a short time before by Dr. Black, led Watt to his
great invention of separate condensation, and since that
time some of the most eminent scientific men have inves-

THEORETICAL LAWS. 307

tigated, theoretically and experimentally, its various pro-
perties. Much has, however, yet to be done ; it is true we
have the experiments of Bobison, Southern, Ure, Dalton,
Arago and Dulong, the Franklin Institute, and last, but
not least, of Begnault in France, and many others of less
importance than these, so that the relations of temperature
and pressure, and the amounts of latent heat, total heat,
and specific heat at all temperatures have now been deter-
mined with an accuracy which we can hardly hope to see
excelled. But there are other properties of which we have
hardly any experimental knowledge at all. To supply some
of these defects I have been engaged upon a laborious series
of' experiments, in conjunction with my friend Mr. Thomas
Tate, with a special view to determine the relations of
temperature and density of saturated steam, and the laws
of the expansion of superheated steam, which have not
hitherto been made the subject of any reliable experi-
ments. These experiments, not yet completed, have not
been unattended with danger, from the necessity of
employing glass tubes and globes at elevated temperatures
and considerable pressure. Some of these tubes exploded,
and on one occasion my assistant, when reading off the
mercury levels, nearly lost an eye from the fragments
scattered about from a violent explosion. Every possible
precaution has however been taken to obtain accurate
results, and as in several respects these are new and
interesting, a brief abstract may be given here in anti^pa-
tion of the publication of the results in a detailed form.

For a perfect gas the law which regulates the relation
between the temperature and volume, and known as Gay-
Lussac's or Dalton's law, combined with the law express-
ing the relation of pressure and volume, known as Boyle's
or Mariotte's law, is expressed in the equation, —

V P _ E + t .gv

V;P, E + t, ^^

X 2

308 ON THE PBOPERTIES OF STEAM.

where V is the volume of the gas at P pressure and T
temperature^ a constant which, according to Kegnault's
experiments^ is 459. Now, assuming that steam follows
the gaseous laws, we have, according to Dumas's experi-
ments, V = 1669, when P' = 14*7 lbs. per square inch,
and at a temperature V = 212° F. Making these substi-
tutions in equation 3, we get for the volume of steam at
any other temperature and pressure

V - 1669 xl^x4i^>^ =365 1^ (4).

P 469 + 212 Pi ^ ^

From this well-known formula all the tables of the
density of steam have hitherto been constructed on which
calculations of the duty of steam-engines have been
founded.

Although the accuracy of this formula, as applied to
steam, has for some time been doubted, yet up to the pre-
sent time no reliable direct experiments have been made
to test its truth, nor are the methods hitherto employed
in determining the density of gases and vapours appli-
cable, in this case, except at the boiling temperature of the
liquid under ordinary atmospheric pressure. But, on the
other hand, theoretical calculations, arising out of the
application of Camot's theory, throw considerable doubt
upon the accuracy of this formula, and these suspicions
have been confirmed by the numerical results of Heg-
nault's magnificent experiments upon latent heat. It is in
att^pting to set at rest this question by direct experiment
that the present apparatus has been devised.

For permanent gases the laws of Gay-Lussac and
Mariotte have been abundantly confirmed by Kegnault's
experiments upon air and carbonic acid. These are nearly
perfect as gases, and the deviations from the gaseous laws
indicated in the experiments are small, except at very enor-
mous pressures. But with vapours the case is widely differ-
ent. And as early as eight or ten years ago Dr. Joule and
Professor William Thomson announced, as the result of

EXPERIMENTS ON ITS DENSITY. 309

applying the new theory of heat to the law of Camot, that
for temperatures higher than 212° there is a very con-
siderable deviation from the gaseous laws in the case of
steam. Later, in 1855^ Mr. Macquorn Bankine gave a
new formula for the density of steam^ independent of Gay-
Lussac's law, and this confirms Mr. Thomson's surmise.
Still these speculations require the confirmation of direct
experiment.

The density of steam is ascertained by placing in a
glass globe, of measured capacity, and exhausted of*its
air, a weighed quantity of water. The globe is then placed
in a bath, and raised [in temperature until the entire
weighed portion of water is converted into steam. The
temperature at which this happens is noted, and we have
thus the three elements for calculating the density, the
temperature, the volume and the weight, from experimental
data. The specific volume of steam, at the temperature
noted, is equal to the capacity of the vessel, measured by
the quantity of water it would contain, divided by the
weight of water introduced into the globe. By employing
different weights of water the density at any number of
temperatures can^be ascertained, and a new formula de-
duced from direct experiment.

Two difliculties, however, have to be overcome. First,
the pressure of the steam renders it necessary that the
glass globe should be heated in a strong and, therefore of
necessity, opaque vesseL Hence the temperature at which
the water is vaporised cannot be determined by direct
vision. Secondly, as steam rapidly expands in volume for
any increase of temperature beyond the temperature of
saturation, it would in any case be impossible to decide
by the unaided eye the exact temperature at which all the
water became vaporised. The slightest error in deciding
the temperature of saturation would vitiate the experi-
ments, and render the results of no value.

X 3

310

ON THE FBOPEBTIES OP STEAM.

The difficulty thus resolves itself into this, to find some
other test sufficiently delicate to determine the point of
saturation. This has been overcome by what may be
termed the saturation gauge, and it is in this that the
novelty and value of the present method consists.

The simplest form of this gauge may be illustrated by
the diagram, fig. 71. Suppose two globes a and b, freed
from air, and connected by the bent tube G d, which con-
tains a portion of mercury* Suppose enough water in-
troduced into A, to be vaporised at a temperature of

Fig. 71.

290° Fahrenheit, which corresponds with a pressure of
50 lbs. ; and let any larger quantity be introduced into B ;
and let the water in A be separated from that in B by the
mercury column c d. If now the globes be heated, the
water in each will go on vaporising, and the pressure in
each will go on increasing uniformly, until all the water
in A is converted into steam« As soon as this point is
reached the mercury columns will change their level, the
column c rising nearly two inches for every degree
Fahrenheit above the saturation point. The instantaneous
rise of the column is the indication of the temperature of
saturation. The cause of it will be perceived. As soon

APPLICATION OP EXPEBIMZHTS.

as the water in A is vaporised
the pressure in that globe prac-
tically ceases to increase ; bat as
water still remains in b, the
pressure in that globe increases
about one pound for every de-
gree Fahrenheit. The unequal
pressure on the mercury column
c D causes the rise observed.
The increase of pressure result-
ing from vaporisation at 290"
is about twelve tjmes the corre-
sponding increase for super-
heating or expansion, and for
other temperatures the differeoce
is about the same.

The application of this prin-
ciple is obvious. Fig. 72 repre-
sents one of the forms of appa-
ratus which has been constructed
and employed with success, a
is the measured globe with a
graduated stem into which the
weighed portion of water is in-
troduced, after a Torricellian
vacuum has been formed. It is
placed in the copper boiler b,
and its stem i, i, passes down
the glass tube o, o. The boiler
B is fitted with a cover, blow
off cock p, and thermometer t.
To heat the apparatus coils of
gas jets S| G, are employed, and
the temperature of the glass tube
o, o, is regulated by the bath,

312 ON THE PBOPERTIES OF STEAM.

G, G, of oil or sulphuric acid for safety placed in a sand
bath. The rise or fall of the columns of mercury a and
6, of the saturation gauge is observed through the strong
glass tube o^ o. As soon as column a in the globe stem
rises and b falls^ the temperature of saturation has been
reached^ as the steam in the boiler B is of course always
in the condition of saturation.

The experiments have been arranged and carried out
with the co-operation of my friend Mr. Thomas Tate
with the greatest accuracy and care, and under our own
immediate direction, with the aid of my assistant, Mr.
Unwin. It is hoped that the results, when pursued up to
high pressures, will prove of great scientific importance
and practical utility.

The experiments have been completed between the
temperatures of ISG** and 290** Fahrenheit, which corre-
spond to the pressures of 2*6 lbs. or (12 lbs. less than the
atmospheric pressure), and 60 lbs. per square inch, but
they are being extended to higher pressures, and a special
series has been instituted to ascertain the law of expan-
sion. The results abundantly show that the vapour of
water does not accurately obey the gaseous laws. "We
have found the density of saturated steam always greater
than that given by the gaseous laws, even at low tem-
peratures.

The following simple formula very nearly expresses the
results of the experiments as to the relation of density and
pressure of saturated steam, the relation between pressure
and temperature having been already determined.

Let V be the specific volume of the steam, or the ratio
of the volume of the steam to that of the water which
produced it.

P=the pressure in inches of mercury, then we find

V« 25-62 +i^ (^^-

LAWS OF SUPERHEATING.

313

Table of MesnltSf showing the Relation of Density and

Pressure of Saturated Steam.

No.

Pressure.

Temperature,
Fahr. o.

Specific Volume.

Propor-
tional error
of formula.

In lbs. per
square inch.

In inches of
Mercury.

From ex-
periment.

By formula
(5).

1
2
3
4
5
6
7
8
9

2-6
4-3
4-7
6-2
6-3
6-8
8-0
9-1
11-3

6-35
8 62
9-45
12-47
12-61
13-62
16-01
18-36
22-88

136-77
155-33
159-36
170-92
171-48
174-92
182-30
188-30
198-78

8266
5326
4914
3717
3710
3433
3046
2620
2146

8183
5326
4900
3766
3740
3478
2985
2620
2124

■ 350
+ 76

— 97

9'
11
12
13
14

26-5
27-4
27-6
33-1
37-8
40-3
41-7
45-7
49*4
51-7
55-9
60-6
66-7

53-61

55-52

55-89

66-84

76-20

81-53

84-20

92-23

99-60

104-54

112-78

122-25

114-25

242-90
244-82
245-22
255-60
263-14
267-21
269-20
274-76
279-42
282-58
287-25
292-53
288-25 .

941
906
891
758
648
634
604
583
514
496
457
432
448

937
906
900
758
669
628
608
562
519
496
461
428
456

_ 1

235

+ T5o

+ 156

+ 166

The above table exhibits accurately the results at which
w^e have arrived in regard to saturated steam ; we have
also obtained some results on the rate of expansion of
superheated steam. These results are at present less
complete than those upon saturated steam,, as they do not
range more than twenty degrees of temperature, in each
case, above the maximum temperature of saturation.
They appear, however, to show conclusively, that near
the saturation point steam expands very irregularly^ thus
agreeing with what we know of other bodies in their phy-
sical relations at or near the point at which they change

314 ON THE PBOPERTIES OF STEAM.

their Btate of aggregation. Close to the saturation point
we find a very high rate of expansion^ but this rapidly
declines as the steam superheats^ and at no very great
distance above it the rate of expansion nearly approximates
to that of a perfect gas.

Thus, for instance^ in experiment (6) where the point
of maxim ^m saturation was 174**'92, between this and 180°
the steam expanded at the mean rate of j^^ whereas air
would have expanded ^^ only ; but on continuing the
superheating^ the coefficient was reduced between 180° and

200** from yio" *^ tsT* ^^^ ^^^ ^^^ ^^^ coefficient would
have been -^^^ or almost exactly the same, and this rule
holds good in every experiment ; a high rate of expansion
close to the saturation point diminishing rapidly to a close
approximation to that of air.

315

APPENDICES.

APPENDIX L

ON THE BESISTANCE OF BASALT TO CRUSHING.

SiNOE the paper on Stone was printed (p. 129), I have had an
opportunity of testing the resistance of Basalt, or Whinstone,
a rock which does not find a place in the list given in that
paper. The following results were obtained : —

Specimen 1.

Height 1*26 inches.
Area 1*22 x 1-24= 1*5128 sq. inches.
Fractured with a weight of 17,418 lbs.
Crushed with 17,866 lbs.
Equivalent to 11,756 lbs. per sq. inch.

Specimen 2.

Height 1*38 inches.
Area 1-26 x 1*25= 1*6760 sq. inches.
Fractured with 17,418 lbs.
Crushed with 19,914 lbs.
Equivalent to 1^,643 lbs. per sq. inch.

Specimen 3.

Height 1*38 inches.

Area 1*26 x 1*26 inches =1*5876 sq. inches.
Crushed suddenly with 18,274 lbs.
Equivalent to 11^510 lbs. per sq. inch.

316 APPENDIX II.

All the above specimens fractured by vertical fissures split-
ting up into thin prisms, wedge-shaped usually at one end.
The mean crushing resistance of the above specimens is there-
fore —

lbs.

(1.) 11,755
(2.) 12,643
(3.) 11,510

Mean . . . 11,970=5*3437 tons per sq. inch.

The mean of three experiments on Granite gave 11,565 lbs.
per sq. inch for the crushing resistance of that substance, and
for Grauwacke from Penmaenmawr it was found to be
16,893 lbs. per sq. inch. The Irish Basalt is, therefore, equal
in strength to the Granite, but inferior to the Grauwacke in
the ratio of TO to 1*4.

APPENDIX II.

ikiR. Grantham's views on the strength ob iron ships.

Since the above Lecture was written I have had an oppor-
tunity of reading Mr. Grantham's paper on the Strength of
Iron Ships, and it is gratifying to me to find that that gentle-
man takes precisely the same views as I have expressed above
in regard to the weakness of our present construction of iron
vessels. He adduces an additional reason for increasing the
strength of the upper part, viz. the tendency of very long
vessels to hog. " It is well known," he says, " that many iron
steamboats are now employed in carrying heavy cargoes,
whose length is eight times the beam, and I have frequently
examined one vessel, that has sailed round the world, whose
length is nine times the bo^m ; nor is there anything in these
vessels which would lead to the conclusion that such propor-
tions are excessive. . On the contrary, with improved construc-
tion, a much greater length may be ultimately attained,

APPENDIX II. 317

especially in large vessels* The maximum of length in wooden
ships has oilten been attained, and probably a proportion of six
times the beam has seldom been exceeded, without showing
unfavourable results, when heavy weights bad to be carried.

^' I shall best explain my views by describing the result of
a calculation I lately made for the purpose of giving evidence
in an important trial. The object sought was, to ascertain
whether a vessel loaded as this was would rise or fall at the
ends, or, in popular language, whether she would sag or hog.
This ship was built of timber, with fine lines, rather light
ends, and the cargo very evenly distributed ; she was 225 feet
long, and 42 feet beam. For the sake of the calculation the
longitudinal elevation was divided into ten equal parts. The
displacement of each section, the weight of the ship, and cargo
also of each section, were calculated, when it was found that
the ends were depressed by a force of 220 tons, and thus threw
a strain on the centre equal to that weight multiplied by the
leverage.

" The tendency, as above observed, is to build iron ships,
especially iron steamers, much longer and finer than this vessel ;
it is clear that the excess of weight over displacement at the
ends will increase in the same ratio, unless precautions are
taken to reduce the weight there. Great attention has been
paid to this subject in the timber built steamers of America ;
and it is found 'that vessels which to us appear dangerous,
from the extreme height of deck-houses and machinery amid-
ships, are plying throughout the year on their wild Atlantic
coast with comparative safety.

*' Now it is quite clear that a vessel should be so constructed,
and, if possible, so loaded, that when in smooth water the weight
should as nearly as possible correspond witli the displacement
of every portion."

In regard to the distribution of material in ships as now
constructed, Mr. Grantham expresses himself strongly. '^ I
think I shall best serve the cause I have so long advocated, by
saying distinctly, that in my opinion a large proportion of the
material now used in iron ships is worse than useless." ....
<< Experience has confirmed the impression which would arise

318 APPENDIX III.

upon anj unbiassed mind, on reading the specifications of
manj of our finest ships, viz. that thej would first show weak-
ness in the centre, the scantling given to the ends being in

general out of all proportion to that of the midships."

" The Great Eastern is perhaps the only large vessel where this
question has been fairlj dealt with, the only one where the
girder principle has been effectually applied, and though the
exact form there adopted could only be applied in very large
ships, yet the principle is correct, and probably the proportions
also."

APPENDIX ni

LETTERS TO THE "TIMES** ON THE VTRECK OP THE ROYAL

CHARTER.

/. — To the Editor of the Times,

Sir, — Among the many and mighty inventions and adap-
tations which have contributed to make this country and this
age famous, a conspicuous place must be given to the applica-
tion of iron to shipbuilding. Without it England's mercantile
marine could scarcely have kept pace with the marvellous
growth of her commerce, and oceanic steam navigation would
yet have been in its infancy. Even Brunei's genius would
have quailed in attempting the construction of the Great Ship
in any other material ; and it is scarcely too much to say that
the abundance and richness of the ferruginous ores which are
found in this island, and the facilities for their reduction
placed to our hands by nature, compelled our naval con-
structors to direct their attention to the use of manufactured
iron in building vessels.

The iron ship, when well built, is indeed stronger, safer, and
more durable than any other, and yet if we search the records
of those disasters to which all seagoing ships are exposed, it
will be found that the most destructive and appalling have
occurred in iron bottoms. I need only call to mind the wreck

APPENDIX in. 319

of the Birkenhead, which will find a place in history as the
scene where the disciplined bravery and devotion of our
soldiers were nowhere more conspicuously displayed, and that
awful and heartrending catastrophe which within the last few
days has carried sorrow and anguish into hundreds of homes.
Yes,, while the hearts of relatives are yet bleeding, and the
public is stunned with the immensity and suddenness of its
loss, while many would try to bury their grief in oblivion, and
others would prefer to contemplate in silence such an illus-
tration of the mysterious ends of Providence, I conceive that
the lessons which the loss of the Royal Charter is calculated
to afford ought not to be overlooked, and that the causes of a
wreck so sudden and so complete should be most promptly and
searchingly investigated.

I would, therefore, very earnestly and prominently bring
under the notice of your readers certain general features and
practices in the construction of iron vessels which in my
opinion are in the last degree dangerous and reprehensible. It
would seem to commend itself to the common sense of every
man, that in building an iron sailing or steamship which is to
be subjected to all the strains and bufietings of tempest-tossed
seas, which will be freighted with hundreds of human beings
and the most precious cargoes, and which must run the risks
of collisions and strandings, none other than the very best and
strongest materials should be employed. The toughest iron,
the best seasoned spars, and the stoutest planks and ropes
should alone find places in such a venture. But in our ordi-
nary every-day practice is this the case ? Is not any kind ^f
iron thought good enough to build a ship with ? What is the
meaning of " boat plates " being the lowest priced in any iron-
maker's list ? If we pay 2SL or 30/. a ton for the plates of
which a locomotive boiler is made, why should we give only
8/. 10*. or 9/. per ton for those of which a ship is built ? If
safety can only be bought at the high price in the one case,
are we not courting disaster with the low price in the other ?
Who will draw the fine line of distinction in moral responsi-
bility between the directors of a railway company who should
take your fare, place you in a comfortable first-class carriage,

320 APPENDIX III.

and drive you at forty mrles an hour over a viaduct which was
miserably insecure, and the owners of vessels who send passen-
gers to sea in ships sheathed with plates which are as brittle
as glass ? The only answer to this question in the way of
excuse is, I fear, that most men are really and truly ignorant
of the facts. In the eyes of the merchant in London or
Liverpool, who orders the building of a ship, iron is iron. He
probably does not know that in this material there are as many
shades of quality as there are in the wines or fruits which all bear
one common name, and yet I am within the mark when I say
that he might by paying 21. or 3/. per ton increased price upon
the plates forming the outward sheathing of his ship immensely
increase the vessel's strength and durability.

With good well-worked plates, where the fibre of the iron is
ductile and tenacious, and where these plates are well and
judiciously fastened together, no vessel, even if wrecked in
such a gale as that of last Tuesday, would break to pieces so
suddenly and so utterly as the Royal Charter seems to have
done.

But built of the " boat plates " of the present day, God help
the human freight of the ship that strikes upon a rocky
shore !

I would therefore advise shipowners when contracting for
new vessels, instead of being satisfied with a specification
which provides good ordinary " boat plates " to be used, and
which are, in fact, about the most rubbishy quality of iron
which is made, to insist that the sheathing should all be of best
b^t, or double-worked quality. In a vessel of 1000 tons it
would not increase the cost 500^., and the value is gained in the
greater strength and durability of the ship, to say nothing of
the lives that it may possibly save.

Further, I would caution all well-disposed shipowners to
look with great suspicion upon the cheap offers which are con-
stantly laid before them as temptations to order ships. To any
one conversant with a ship's value, what other construction
can be put upon a contract for a vessel of 1000 tons, with the
most expensive outfit, for 13/., or 13/. 10*., or even 14/. per
ton measurement ready for sea, than that the builder means to

APPENDIX III. 321

employ bad materials and scamp his work ? He begins upon
such an order with a determination either to cheat his cus-
tomer or cheat his creditors. But such vessels are built on the
Clyde, the Tjne, and elsewhere, and I maintain that the ship-
owner, in buying them, shares with the builder the moral
responsibility of a great guiltiness, for they are deliberately
launched and freighted to go to the bottom.

I am, Sir, your faithful servant, .

Amicus.

Manchester, Oct 31.

11. — To the Editor of The Times.

Sir, — In noticing the letter on iron shipbuilding which I
addressed to you soon after the wreck of the Royal Charter,
you most correctly observed that in making the statements I
did it was neither my intention nor my wish to point any par-
ticular charge against the owners or the builders of that unfor-
tunate ship. To have done so while the inquiry before the
coroner's jury was unfinished, and when we were promised an*
official investigation by officers appointed by the Board of
Trade into the causes of the disaster, would have been most
inconsiderate and most unfair. I therefore confined my charges
to certain hurtful practices both in the construction and the
purchase of iron ships, which may be said to be of almost
general pertinence, and therefore well worthy of attentive
consideration. These evils are — first, the frequent use of the
worst quality of iron made, and called '' boat iron," in the
construction of ships ; and, second, the frightful risks t« life
and property which the public is called upon to sustain in
consequence of a competition among shipbuilders, encouraged
by shipbuyers, wherein price alone is considered, and quality
(which includes durability and safety) is entirely ignored.
'While dealing with these general questions I ventured,

322 APPENDIX III.

however, to express an opinion that no properly proportioned
vessel, if built of well-worked ductile iron plates, and well
fastened together, would have shivered to atoms so suddenly as
the Royal Charter seems to have done, and to this opinion I will
still firmly hold for the sake of the interests involved and the
thousands of lives now afloat in our iron ships.

It is true that the Welsh jury found a verdict acquitting
everybody of blame, and the able report of Mr. Mansfield,
which I have just read most carefully, states that from the evi-
dence he had arrived at the conclusion that the Royal Charter
was, at the least, fully equal in strength to the average ships of
her class at the same date (1855).

I do not quarrel with either verdict or report. Upon the
evidence brought before the two tribunals the decisions could
not have been different. But if that evidence had been made
more comprehensive ; if the captain or others in authority had
been saved to tell us of the ship's behaviour in heavy weather ;
if we had had more general and extensive tests of the strength
of the ship*s material ; if some calculations had been furnished
of her strength considering her hull as a beam supported in
the middle and unsupported at its ends, which must have
been very nearly the ship's position when she parted amidships ^
and if we had been informed whether the plates used in her
construction were really ** boat plates," or " best plates," and
where they had been made, the public would have been inclined
to attach greater importance to the conclusions arrived at.
Because, if those conclusions were indisputable, I confess they
would give rise in my mind to many most anxious reflections —
reflections which would be so painful to myself and to others,
that I would stifle their expression rather than create alarm by
their publication.

We are told that the Boyal Charter was fully equal in,
strength to the ships of her class. Am I, therefore, to believe
that every iron ship which shall drift during a storm on to a
rocky shore, or which shall sustain an equally severe shock by
collision in mid-ocean with another ship, must of necessity
tumble to pieces in the short time -^ the few awful minutes —

APPENDIX III. 323

which sufficed to hurry the Royal Charter^s wretched pas-
sengers and ship's company into eternity ? Am I to believe
that there is no hope for the human freight of such a ship
stranded within fifty yards of land, and with a hawser already
sent on shore — that it is their inevitable fate to be engulfed
by the angry waters, struggling and clinging together ? Are
sea-voyagers to be told that, of all the thousands of iron ships
afloat, the fate of every one is almost instantaneous and utter
destruction, should she strike upon some hidden reef?

Surely these are unnecessary alarms and suspicions to
entertain, even after so terrible a tragedy as the wreck in
Moelfra Bay ; and yet a belief in them is a legitimate deduc-
tion from the admission of the Royal Charter being, for her
class, a vessel of fully average strength.

And surely it is a more probable, a more charitable, and a
more comfortable inference, that some hidden source of weak-
ness in the materials or in the construction of the ill-fated ship
itself was the cause of that sudden and terrible crash, than
that so many we love and so much that we value &re now and
always intrusted in fragile and unsafe ships.

There are not wanting many and pertinent examples of
wrecks to iron ships which point to the very opposite conclu-
sion, proving their strength and safety, and showing how
tenaciously they will hold together under severe and lengthened
strains. The Great Britain^ it will be remembered, was left
bumping upon the rocks in Dundrum Bay during a whole
winter, and even in that exposed position was thought so safe,
and so far from destruction, that her crew remained on board.
In the case of the Vangtmrdy wrecked on the west coast of
Ireland, and exposed consequently to the full swell of the
Atlantic, it appears she remained in a position in which, from
midships to the stern, she was entirely unsupported, and yet
was so little injured that, in the words of one who went over
to examine her, ^' although beating hard upon the rocks for so
many days, no part of her engines was deranged, and they
were kept constantly at work." Again, the Royal George^ an
iron steamer running between Liverpool and Glasgow, and a

T 2

324. APPENDIX lU.

vessel of unasnal length compared to her beam, got on a rock
near Greenock at high water^ and as the tide receded it was
found she rested nearly on her centre, with both ends entirelj
unsupported. No vessel could have been subjected to a severer
strain than this, and jet she als« was hauled oiF at the next
tide entirely uninjured. I could adduce numerous other
instances to prove my point that well-constructed iron ships
are very safe — in fact, safer than any wooden ships can be
made, because the iron ship is by the riveting and proportion-
ing of the plates made into a firm continuous mass of uniform
strength ; whereas a wooden ship is composed of innumerable
pieces, which at best can only be imperfectly joined together.
But then greater circumspection is required in the selection of
the material for the iron than for the wooden vessel. A shaky
or rotten piece of oak, teak, or elin is easily detected ; and if a
shipbuilder use deal where oak should be placed, at least his
dishonesty is readily discovered* But, if I may be permitted
the paradox, iron is not always iron. It is sometimes*rubbisb,
and in this*category I would unhesitatingly place all ^'boat
plates." It is not that even in these inferior plates pieces may
Qot be found which shall come up to and even surpass Mr.
Fairbairn's standard of the average tenacity of good Stafford-
shire plate ; but, being made chiefly from cinder iron, it ia
their inequality and uncertainty which is most to be dreaded.
The strength of the whole is that of the weakest part, and
when I tell you that out of the same "boat plate," or iron of
that quality, two pieces have been taken, one of which sustained
22 tons to the square inch of section, while the other failed
at 5 tons, I have said enough to show why this dangerous
material should be at once discarded in building ships, and the
price of "best plates " be paid to ensure the exclusion of cinder
iron from their manufacture. Boat plates are shams. They
are got up to deceive by appearances. Smooth and well-
looking on the surface, the source of mischief lies hidden
underneath — rotten at the core, like the grub-eaten fruit
whose tempting skin conceals the tiny hole by which the
insect has entered. But this iron is a curse as well as a decep*

APPENDIX III. 325

tion, for while you may be angered at the Yankee who has
sold jou wooden nutmegs, or the grocer who sands his sugar,
or the petty swindler who sells you 100 yards of sewing cotton
** warranted " 200, 1 know no words strong enough to condemn
the practice of makers and buyers alike, who in structures
where the safety of life and limb is at stake, will willingly and
knowingly, and for gain's sake alone, imperil the existence of
their fellow-creatures.

I am, Sir, your faithful servant,

. Amicus.

1 3

INDEX.

Page

Agricaltare, early Egyptian . 162

Boman .... 163

American . • .•I64

implementa . . .166

steam plonghing . .171

reaping machines . .176

duty of the farmer . .184

Amiens^ letters to **The Times'* 318

Angle of fracture in crushing . 63

Apparatus for experiments on

the collapse of iron . 3
crashing of glass . . 54
bursting of glass • . 65
collapse of glass . • 74
tenacity of iron . . 98
density of steam . . SflO
Arkwright, Bichard . . 206
Atmospheric engine . .194

Bakewell, Robert • . .165
Basalt, resistance to crushing .315
Bell's reaping machine . .177
Boat plates . . . .319
Boiler plate, tenacity of, at ele-
vated temperatures . .96
Boilers, new principles in . 298
Boydell's traction engine . .172
Brick, resistance to crushing . 140
Brindley, as an engineer . .201
Bulkheads in ships . . . 276
Bursting, resistance of iron and

lead to . . . .26
formulsB of . . .39
tables for boilers . • 42
resistance of glass globes
and cylinders to . .63

Butt-joints

17,45

Page

Canals 202

Cellular system in ships • 263, 273
objections to . • .269
Chain-rivetiDg . . .259
Charter t Royals loss of . .318
China, arts in . . . . 187
Clarke on steam cultivation . 172
Collapse, resistance of wrought

iron vessels to . I, 300
steel tubes to . . .21
elliptical tubes to . * 23
formulffi of for iron tubes . 30
for elliptical tubes . . 38
of the North-Western

boilers . . • .43
of glass globes and cylin-
ders .... 74
on board the Great
Eastern . . . 304
Com mills, Pompeian . .189
Cort, Richard, ill usage of . 208
Cosmo, de Medicis, description

of Worcester's engine . .192
Cotton spinning . . . 206
Coulomb's law departed from

in the case of glass . . 63
Cranes, first tubular iron. . 282
advantages of . . ^ 289
colossal 60 ton . . .291
steam .... 295
travelling. . . . 296
Crushing, resistance of glass to 53
of sandstone to. . . 131
of other stone to . 136, 139
influence of bed of stone

on • « . « 138
of brickwozk to • • 140

328

INDEX.

Page
Crashing, reaistanoe of basalt to 315
Caltivator, steam, Fairbairn's,

172, 175
Hoskjn's .171

Deck of ships, new constrac-
tion of ... . 864

Deflection of cranes . 288

Distribution of material in
ships 259

Drainage of land . . . 170

Eastern, the Great . 263, 271 , 318
explosion on board . . 304
Education, elementary . .147
juvenile . • . .150
adult . . • . 154
Elongation of iron . . .126
Expansion of steam . .312
Experiments on resistance of
cylindrical iron vessels
to collapse ... .7
of steel tubes • . • 21
elliptical iron tubes . . 23
iron tubes to internal pres-
sure . . . .26
of leaden tubes to internal

pressure • .. .. 28
on North-Westem boilers 43
of glass to collapse ^ 74

glass to crushing • ^ 53
on tenacity of glass • . 50
glass vessels to bursting • 63
on tenacity of iron at vary-
ing temperatures . .. 96
on reaping machines .178
on iron sMps, need of .. 280
on cranes . . . 285
on the density of steam . 306

Fibre, influence on strength of
iron . ...... 113

Fines of boilers, danger of,

2, 41, 299
. proportions of . . .. 305

Formula of resistance of iron

to collapse . =30, 303
of strength of elliptical ves-
sels . . .. « 38

of cylindrical vessels to

bursting ... 39
of density of steam . 307,311

Page
Formnlss of resistance of glass

to collapse . . .86
of resistance of glass to

bursting . . .92

transverse strength of glass 94

Fowler's steam plough . . 1 73

Fracture of glass, form of . 59

repeated, eflect on strength

of iron. . . . 125

Gay-Lussac's law • • . 307

Glass, properties of. . .47

composition of. • .48

specific gravity . .49

tenacity of . . .50

compressive resistance . 53

resistance to bursting 63, 92

. resistance to collapse 74, 86

transverse strength . . 94

Grantham, Mr., views on iron

shipbuilding . . .316
Granite, resistance to crushing,

136, 139

Hoskyn's cultivator .

171

Iron„tensile strength at elevated

temperatures • « 96
manufacture . . « 207
in miilwork . « « 197
ships, strength of . 244, 257
quality of,in ships, 266, 271,31-9

Joints, butt and lap . . 17, 45
riveted, proportions of . 262
in ships • « • . 260

Labour, love of . • .152
Lead tubes, resistance to burst-
ing . . . .28

tenacity of . . .40
Locomotives, first . • . 241

power of . « . . 242

Machinery of agriculture. . 162
Mariotte*s law . • .307
Miilwork, early • . .196

Newcomen*s engine. . .194

Fapin's cylinder and piston . 193
Ploughs, cattle . • .167

INDEX.

329

Page
Ploughs, steam . . .171
subsoil . . . .170
Forphjiy, resistance to crash-
ing 139

Pottos self-acting valves . 196

Ra&nhill competition
Reaping machines .
Begnault*s experiments
Kivet iron, tenacity of
Rivets, proportions of

241
176
307
114
262

Saturation gauge . . . 309
Savery's engine . . . 192

Shafting 199

Shell and flues of boilers,

strength of . . . .41
Ships, strength of . . . 244
recent changes in propor-
tion .... 245
ordinary constraction .246
formulee of strength . . 248
weakness of . . .251
proposed standard . ..257
distribution of material . 259
cellular system in . .273
for war .... 281
Smeaton's works . • . 200
Chasewater engine . .194
Smith, of Deanston, subsoil

plough. . . .170
steam plough . . .173
reaping machine . .177

Page

Specific gravity of glass . .49

of stone .... 138

Steam, in agriculture • .170

engine, Worcester's . .192

Savery's . . . .192

Newcomen*s • . .194

Watt's . . ... 204

density of . . . 305

superheated . . .312

Steam power, total in England 206

Stephenson's Rocket • .241

Stone, properties of. . .129

resistance to crashing 130, 315

water absorbed by . .137

sandstone. . .141

limestone. . . .142

basalt . . .315

Stringers in ships . . .246

Success in life, the conditions

of . . . 157. 167, 203

Tenacity of lead ... 40
of glass . . . 50,92
of iron at elevated tem-
peratures . . .96

Timber, resistance to crushing . 144

Watt's genius . . . 204

Worcester, engine of the Mar-
quis of ... . 192

Young, Arthur

. 165

J??^^

THE END.

VOKDOV

PBIVTXD BT SPOTTIB'VroODX AKD CO.

KBW*STBKIT SQrA.RX

BY THE SAME AUTHOR.

Third Edition, thoroughly revised, with 8 Plates of Figures
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INFORMATION FOR ENGINEERS.

Being a Series of Lectures delivered
before the Working Engineers of Yorkshire and
Lancashire. With Appendices, containing the Eesnlts of Ex-
perimental Inqniries into the Strength of Materials,
the Causes of Boiler Explosions, &c.

IHE following subjects
JL are comprised and il-
lustrated in this work : — The
construction of boilers, with
rules for calculating their
strength, &c. ; the causes of
boiler explosions ; the con-
sumption and economy of fuel,
and the prevention of smoke ;
the necessity of incorporating
the knowledge of science with
the practice of the mechanical
and industrial arts; metallic
constructions applied to ship-
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the Advancement of Science,
on the resistance of cylin-
drical vessels to compression
from an external and sur-
rounding force. These expe-
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external strain are given in a form
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mU£ AND MILL-WOKK

THIS work is intended to
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intelligible maoner, the prin-
ciples of construction, propor-
tion, and strength of all the
machinery falling within the
province of the millwright;
and to illustrate the machinery
BO described, and the general
arrangement of various de^
scriptions of mills by examples
taken from the Author's own
practice. It treats, first, of
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mechanism in general, and the
elements of which the more
complex machines are com-
posed. In the next section
prime-movers are discussed,
beginning with those depend-
ing on water power. The
principles of hyarostatics, the
collection, measurement, store-
age, and application of water
are treated of at considerable
length. The construction of
the various forms of overshot,
undershot, breast and Ponce-
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thods of ventilation are de-

scribed. Turbines and the
simpler water-pressure en-
gines are also treated of, and
especially that introduced by
Mr. James Thomson, and
known as the vortex wheel.
The properties of steam are
then considered, and a resume
is given of the Author's own
experiments on the density of
saturated steam and the ex-

?ansion of superheated steam,
he various forms of steam-
engines and boilers employed
in mills are illustrated. In
the next section transmissive
machinery is treated of, in-
cluding framing, shafting,
couplings, gearing and the
principles of the formation
of the teeth of the wheels.
Another section is devoted to
examples of various descrip-
tions of mills, including corn
mills, cotton, flax, and woollen
mills ; and lastly, other miscel-
laneous machinery usually con-
structed by the millwright, in-
cluding cranes and machinery
for lifting, wIU find a place..

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CLASSIBIBD INDEX

i^onltnre and Knral Affiuii

ssisSsS'

Sf"

Un'i ttUttnuTf of ArU, ft

FhI'i Blulch of Kr B. P«l'r
CbiiTulcr '

WfttcrtgB'i AnUtb^gnidiT ud Ei

Baolu of Qeneral TTUIitj.

Botany and Oardaniof .

Commerce and KtiBtxtilt

OUb.rl'iLo.toIBn*li.x •

' Criti^UL, TTIftftiyi **»J Kn&oin,

nlIW«T>tenni .

Oflographr and. AtlaBSi.

Juvenile Boolca.

Xedicint, florgtg^, Ae.

I
I
MiMdUiMou litantare.

■WhlW A RIdfllelljdkaSioUgiunr
Tvnn'a EniFllib-GrHk I^tknn -

Hfttnral Slatacj in gtntjtl.

Ove-Volame SnoftlspwdiH sad

Matioiiuiea.

Ditlft'i Uiblbelua

MiTTiT'ibniJfipadli
BliBT% BilUili OuHUt

B«U^Qi and Xoral Vorki.

SUphcDt fi«lFila^Ucii] BlofnphT^

Poetty kud the Smdu.

OATAioaus.

■ ftHim M>i f ■luiii

The 8ci«noH in gaoanl ftsd
" ttheautOei.

■^ nUoMnlir tf Hiun'.
» I M IhijjSli a ElnlM___ _^ .

Bnntl'SpoTti.

■Ina'l DicU4B4rT of Sj

Id SliH [Tlu) *■
batutjii « AJMlmg

Taterlauy Hedicins, fte.

MnniniM'iTMiiiiiiii iiiiir *''

FHk>,FliMi,ni<ei>ain .
Bimirt OlHlm *f McnOi 1

Vmrtfra. in InliKr i

ToTk* of Fiction.

ALPHABETICAL CATALOGUE
of

NEW WORKS and NEW EDITIONS

rCBLISHKD B1

LONaMAN, GREEN, LONGMAN, AND ROBERTS,
PATERNOSTER ROW, LONDON.

Miss Acton^s Modem Cookery

for Private Families, reduced to a
System of Easy Practice in a Series of
careftilly-teBtea Receipta, in which the
Principles of Baron Liebig and other
eminent writers have been as much as
possible applied and explained. Newly-
revised ana enlarged Edition ; with 8
Plates, comprising 27 Figures, and 150
Woodcuts. Fcp. 8vo. 78. 6d.

The Afternoon of Life. Sy the

Author of Momitiff Clouds. New and
cheaper Edition. Fcp. Bvo. 5s.

Agassiz. — An Essay on Classi-
fication [the Mutual Relation of Or-
ganised Beings]. By Louis Agabsiz.
8vo. 12s.

Aikin^s Select Works of the

British Poets firom Ben Jonsou to
Beattie; with Biographical and Criti-
cal Prefaces. New Edition, compris-
ing Selections ftom more recent Poets.
8vo. 18e.

Alexander.— Salmon-Fishing in

Canada. By a Resident. Edited by
Colonel Sir James Edwabd Albx-
ANDBB, E.C.L.S. Map and Woodcuts.
Post 8vo. 10s. 6d.

Arago (F.)— Biographies of Dis-
tinguished Scientific Men. Translated
by Admiral W. H. Smyth. D.C.L.,
F.R.S., &c. : the Rev. Babbit Powell,
M.A. : ana Robbbx Obaiti, M.A
F.RJLS. 8V0.186.

■•»

Arago's Meteorological Essays.

With an Introduction by Baboit Hum-
boldt. Translated under the super-
intendence of Lieut.-Col. E. Sabinb,
R.A., Treasurer and V.P.R.S. 8vo. 18s.

Arago's Fopolar Astronomy.

Translated and edited by Admiral
W. H. Smxth, D.C.Ly F.R.S. ; and Ro-
bbbx Geant, M.A., F.R.A.S. With 25
Plates and 353 Woodcuts. 2 vols. 8vo.
price £2. 5s.

Arnold. — Merope, a Tragedy.
By Matthew Abnold. With a Pre-
fibce and an Historical Introduction.
Fcp. 8vo. 6s.

Arnold.— Foems. By Matthew

AxsoiiD. FiBST Sbbibs. Third
Edition. Fcp. 8vo. 5s. 6d. Second
Sbbibs, price 5b.

Lord Bacon's Works. A New

Edition, collected and edited by R. L.
Ellis, M. A., Jambs Spbddiko, M.A.,
and D. D. Heath, Esq., Barristei-at-
Law. Vols. I. to V. comprising the
TUviaion ot Philogophieal Works; with
a copious Index. 5 vols. 8vo. price
£4,. 68. Vols. VI. and VII. conipvlsing
the Division of Litercary and Profes-
sional Works, with a full Index. 2
vols. 8vo. price £1. 166.

Baker.— The Rifle and the Hound

in Ceylon. By 8. W. Bakeb, Esq.
New Edition, with 13 Illustrations
engraved on Wood. Fcp. 8vo. 4s. 6d.

Baker. — ^ Eight Years' Wander-
ings in Ceylon. By S. W. Bakeb, Esq.
With 6 coloured Plates. 8vo. ISs.

Barth.— Travels and Discoveries

in North and Central Africa : Being the
Journal of an Exi)editloii undertaken
under the auspices of Her Britannic
Majesty's Government in the Years
18^-1855. By Henby Babth, Ph.D..
D.C.L. With numerous Maps and
Illustrations. 5 vols. 8vo. £5. 53. cloth.

Bate. —Memoir of Captain W.

Thornton Bate, R.N. By the Rev. John
Baillie. New Editton ; with Por-
tr^t and 4 Illustrations. Fcp. 8vo. 5s.

Bayldon's Art of Valuing Bents

and Tillages, and Claims of Tenants
upon Quitting Farms, at both Michael-
mas and Lady-day ; as revised by Mr.
Donaldson. Seventh Edition, en-
larged and adapted to the Present
Time. By Robbbt Bakeb, Land-
Agent and V^mer. 8vo. price 103.6a.

KEW W0BK8 Ain> NEW EDITIONS

Blaek's Practical Treatise on

Brewiiiff, based on Chemioal and £00-
nomical Principles : With Formols
for Pvbtto ft«weT% and Antraettons
for Private Families. 8TO.108.6d.

Blaine's Sncydopasdia of Enral

Sports: or, a complete Acooant, HtBto-
ricid, Praotical, and Descriptive, of
Hunting, Shooting, Fiahinfb Badnc,
Ac, Jiew .BtWionjrevised anacorrectea ;
with above 000 Woodcut Illustrations,
including 20 Subjects from Designs by
JoHirLxBCH. 8vo. price 428.

Bloemfteld.— >Tlie Greek Testa-
ment: with copious EngUsh Notes,
CritLcaLPhllelogicaa, and Explanatory.
Hy adapted to tfaetnrf^Theo-
Lcal Stndvnts aad MlniBtem. Bf the
Rev. 8. T. Bu>oiaai.Vi D.Dw F.S.A.
Ninth Edition. revte«U t Toli^ 8vo.
with Map, £& 8b,

Dr. BloomfieM's festical Anneta-

tions oa the New Testament, being a
Supplemental Toltime to the Ninth
Edition. 8vD^,t4s.

Br. BleemMiff 8 College At Sckool

Edition of the Oreeli Testamentr: With
brief English notes, eUefly Phflolp^ical
and Explanatory. Seventh Edition;
with M19 and In(i»x. Fcp.8vo. T8!.6d.

Br. Sloeoifield^s CoQege ft flckool

Lexicon to the Greek Testament. New
Sditioa, revisML Fepi 8vo; prwe 7s. 6dL

Boase.— Hie Flulosophy of Na-

tore: A Systematic Treaitisa on Urn
Causes and Laws of Natural Pheno-
mena. Bjr HxHST S. BOASX* HD.,
F.R.S., and O.S. 8to. 12s.

i BoydL — A Kamuil ftr WktsA

Cadets. Published with th« sauetfon
and approval of the Lords Commis-
sioners of the Admiralty. By Joav
M'Nbiu^Bots, Captain, R.N. Second
Edition: with 253 Illustrations (13
. coloured). Fcp. 870. 128. 6d«

, Bovnie. -•▲ T^atis» an tiie

Stoam EngkM^ in itv Applicaftion to
Minev, mOB,, Steam NavtintioR. and
Baiiwaysk I^ the Artisan Club. Edited
bj JoHii BomuTB. C.B. New and
greatly improved Edition ; with many
Plates ma Wood Engravingsv 4to.

Bourne's Catechism of the Steam

Engine in its various Applications to
Mmes,. Mills. Steam Na^gation, RaU-
waysk aiidA«ifindtur»i mih Practical
Instructions for the Manufacture and
Mani^ment of Engines of every class.
With 89 Woodcuts. Pep. 8vo. 6s.

Brande*s Bictionary of Science,

Literature, and Art ; comprising the
History, Deseiiption, and Scientific
Principles of every Branch of Human
Knowledge: with the Derivation and
Definition of all the Terms iu general
use. Third Edition, revised and correet-
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Prefeasor Brande'9 Lecrtofes en

Organic Chemistryr aa appliedto If smu-
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Calico Printing, Sugar Mannihcture,
the Fres^vation of Wood, Tanning,
&e. Edited bj J. Scobxesit, M.B.
Fcp. Woodcuts, 7sv Od.

Bray.— The Edscatlon of the

Feelings. By Ceables BBay; Third
Edition. 8V0.5S.

Brewer.?— An Atlas of History

and Geography, firom tlie Commence-
ment of the Cnristhin Era to the Pre-
sent Time: Comprising a Serres- of
gixteen Coloured Maps, arranged in
hronological Order, with Illustrative
Memoirs. S^ the Rer. J. S. Bbvwbb,
M.A. Second Edition, m^MednxLdooT-
meted. Bio^8vQ.128»ed..hai£boaad.

.ftialmont and l^ei^'ii Life of

Wellington. — History of the Life of
Aithur Duke of Wellington: The
MiStary Miefmoirs from tm lYench of
Captaia BlirxEaroira, with AdditifHis
and EmendatioB*;: the PolMeal and
Social LifSa by the Bev. G. R. Gf.£ia,
M.A. With Maps, Plans of Battles,
and Portraits. 4 vols. 8vo. £2. lis.

Breclie.— iPsyclMi<egio«L laqni-

riev, in » Series of Esiiaya hotended to
iHustrate the Infiasnm <a tixe Physical
Organisation onths' Mental Faculties.
By Sir Bbtstjaxot C. BxoioBk. Bart.
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Bx. BaU en. the Xateraftl Xa-

na^enent of Children: in Health and
Dl«eaae. N«wEditi«n. Fcp.8vo.5e.

Br. Bnirs Hints to Mothers on

the Managementof their Health daring
tba Period of Pregnancy and in the
Lying-in Room^ With ax Exposure of
Popular Errors in ooanenoawitktlMse
subjects, &c. ; and Hinteupon Nflnhag.
New Edition. Fcp. 8vo. Saw

FTTBLISnXD BT HOKOMAIT, OBEXN, AlTD CO.

BiuuwaL—ChrigtiMdty and Han-

kind, tiieir Beglunhi«» and ProapeetA.
By Banni C» C. J. BDHWDt, IX D..
]>.CX., D.Ph. BtfiiiK a N«w Edition,
corrected, r»>iiu>delle«L and •xtraded,
of HippolvtHB amd km Jfre^ 7 Tola.
8TO.£5.5».~Or,

1. Hippolytos and hii Age; ok, th« Begin-
ninga and Vrocpects of Chruitianit;. t
vols. 8vo. £1. 10«.

2. Outline of th« Phileaophr of Unirenwl
History appHdd to Lan^ngs and Reli-
gion i containing na Aceount of the Ai-
phabctical Con/eroiees. 2 Toia. 33a.

S. Analecta Ante-Nicaens. 9 vols. 8vo. £S. 2$.

BuBBBiL -« Lyrft €^6nitaixica.

Tranalat^d from the German I9 Cazhb-

KOnc WllTKWOBXK. FlBSX SSSISS,

Hymns for the Sundays and Festivals
ofthe Christian Tear. Sbcoitd Sbxibs.
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Series.

An Edition of tke Fxssc Sksixs of
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under his superinteudence. Fcp. 4to.
price 2l8.

HYMNS from Lvra €f«finanlca, ISmo. Is.

* ,* These aelectiona of German Hymns have
been made from collections nnbliahed in Gm-
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Tolnaieflto

Theologia Qermaniea. Trans-
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BnxuMiL— Egypt's Flaee in UbI-

versal History : An Historical Investi-

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BoBtimg. — The Lii!B of Jabez

Bunting, I>.I>. : With Notices of eon-
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his Son.THOHASPBBCITALBUNTIirQ.

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BvmyaiL^B Bilgxim'a Progress:

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Buxke.— Yieissitiides of Families.

By Sir Bbbkakb Bgbkb, Ulster King
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Biirtoii.-*TlM lake Besieae of

Central Africa : A Picture of Exidora-
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Captain Burton's First Footsteps

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Captain Burton's Personal Nar-
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•

Biskop Butler's Sketek of Mo-
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PostSvo. 7s.0d.

Bishop Bmtler*s General Atlas

ofModem and Ancient Geography; oom-
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l^ the Author's Son. Royal 4to. Ms.

The Cabinet Lawyer: A Popular

Digest of the Laws of England, Civil
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Law Terms. Maxims. Statutes, and
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The Cabinet Gazetteer : A Popu-
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the World. I^ the Author of Th«
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Calvert. — The Wife's Manual ;

or, Pn^ers, Thoughts, and Songs on
Several Occasions of a Matron's Life.
By the Rev. W. Calvbbt. MJL Oma-
mented firom Designs by the Author in
the style of Qimm Elizabeth'9 Prasfer'
Book. Crown 8vo. lOs. 6d.

■KEW WOBKS AKD NBW BDITIONS

Catlow's Fojpiilar Conchology;

or, the Shell Cabinet arranged aooord-
ing to the Modern System: Witli a
detailed Account of the Animals, and a
complete Deflcriptive List of the FMni<-
lies and Genera of Recent and Fossil
Shells. With 406 Woodcuts. Poet
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Cati and Farlie's Book of Em-
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Nations, from J. Catz and R. Fablib ;
comprising 60 circnlar Vignettes, 60
Tail-Pieces, and a Frontispiece com-
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The Text translated, oc., by R. Pigot.
Imperial 8ro. Sis. 6d. cloth ; gr 628. 6d.
bomid in morocco.

Cecil. — The Stud Farm ; or,

Hints on Breeding Horses for the Tnr^
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Cecil's Stable Practice ; or, Hints

on Training for the Turf, the Chase, and
the Road ; with Observations on Racing
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and Handic&pping : AddreBsed to all
who are concerned in Racing, Steeple-
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Edition. Fcp. 8vo. with Plate, 5s.

Chapman.— History of Onstavns

Adolphus, and of the Thirty Years*
Wv up to the King's Death: With
some Aeeomit of its Conclusion by the
Peace of Westphalia, in 1648. By B.
CHAPUAir, M JL. 8vo. Plans, 12s. 6d.

Clough.— Greek History from

Themistocles to Alexander, in a Series
of Lives from Plutarch. Revised and
arranged by A. H. Clouqh, sometime
Fellow of Oriel College, Oxford. Fcp.
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Conington.— Handbook of Che-
mical Analysis, adapted to the Unitary
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INGTON, M.A., F.C.S. Post Svo. 78. 6d.
Also, Tables of Qualitative AnalpBis,
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Connolly's History of the Eoyal

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Conybeare and Howson's Life

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Dr. Copland's Dictionary of

Practicid Medicine : Comprising Gene-
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Bishop Cotton's Instmctions in

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Crowe.— The History of France.

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Cmikshank. — The Life of Sir

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Falkoner.— -DflBdalas; or, the

Oausea and Prindplea of the Snelleoce
of Greek Scviptare. By Edwabd
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Falkener.— Museum of Classical

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Gaxratt^— (MarYols and Mysteries

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Gilbart's Logic of Banking: A

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The Poetical Wozfcs of Oliver

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